Difference between revisions of "Sharp Foods"

From Halachipedia
Jump to navigation Jump to search
Line 24: Line 24:
 
# If the sharp food is cut with a meat knife or cooked in a meat pot and then cooked in a dairy pot or with a dairy spatula or utensil the sharp food is considered not kosher as well as the dairy pot, and the spatula or utensil need koshering. This is true even if the dairy pot, spatula, or utensil is eino ben yomo. This is also true of the opposite case, such as a sharp food cut with a dairy knife.<ref>Dvar Charif 10:13 ch. 185 based on Rama 95:2</ref>  
 
# If the sharp food is cut with a meat knife or cooked in a meat pot and then cooked in a dairy pot or with a dairy spatula or utensil the sharp food is considered not kosher as well as the dairy pot, and the spatula or utensil need koshering. This is true even if the dairy pot, spatula, or utensil is eino ben yomo. This is also true of the opposite case, such as a sharp food cut with a dairy knife.<ref>Dvar Charif 10:13 ch. 185 based on Rama 95:2</ref>  
 
#This is also true if the sharp food cut with a meat knife is fried in a dairy pan with some oil.<ref>Dvar Charif 10:12 ch. 185</ref>
 
#This is also true if the sharp food cut with a meat knife is fried in a dairy pan with some oil.<ref>Dvar Charif 10:12 ch. 185</ref>
===Cut with Meat Knife and Cooked with a Parve Food===
+
===Cut with Meat Knife and Added to Parve Food===
 
# If the sharp food is cut with a meat knife or cooked in a meat pot and then it is cooked with another food, if that second food is mixed with milk there is a dispute if the second food with milk is permitted (''nat bar nat bar nat'').<ref>Badei Hashulchan 96:5 quotes that the Pri Megadim is strict since we treat nat bar nat of a dvar charif like one nat so too with three nat's. (Commonly this is known as the opinion of the Even Haozer YD 96.) However, Rabbi Akiva Eiger argues.</ref> For a case of need it is permitted.<ref>Badei Hashulchan 96:5</ref>
 
# If the sharp food is cut with a meat knife or cooked in a meat pot and then it is cooked with another food, if that second food is mixed with milk there is a dispute if the second food with milk is permitted (''nat bar nat bar nat'').<ref>Badei Hashulchan 96:5 quotes that the Pri Megadim is strict since we treat nat bar nat of a dvar charif like one nat so too with three nat's. (Commonly this is known as the opinion of the Even Haozer YD 96.) However, Rabbi Akiva Eiger argues.</ref> For a case of need it is permitted.<ref>Badei Hashulchan 96:5</ref>
  
===Cut with Meat Knife and Cooked with a Parve Soup in Dairy Pot===
+
===Cut with Meat Knife and Added to a Parve Soup in Dairy Pot===
 
# If an onion was cut with a meat knife and put into a parve soup cooking in a dairy pot that wasn't used within 24 hours for dairy the pot is permitted and the food shouldn't be eaten with dairy.<ref>Dvar Charif p. 179 is lenient since it is nat bar nat of hetera in the pot since it is eino ben yomo. Even for the minhag of the Rama 94:5 it isn't necessary to be strict since we can include the opinion that onions aren't charif.</ref>
 
# If an onion was cut with a meat knife and put into a parve soup cooking in a dairy pot that wasn't used within 24 hours for dairy the pot is permitted and the food shouldn't be eaten with dairy.<ref>Dvar Charif p. 179 is lenient since it is nat bar nat of hetera in the pot since it is eino ben yomo. Even for the minhag of the Rama 94:5 it isn't necessary to be strict since we can include the opinion that onions aren't charif.</ref>
 
# If an onion was cut with a meat knife and put into a parve soup cooked in a dairy pot that was used within 24 hours for dairy, some say that the pot is permitted and the food shouldn't be eaten with dairy.<ref>Dvar Charif p. 176 Chedrei Deah 96 and Maharil Diskin 14 based on the opinion of Shulchan Aruch 95:3 that nat bar nat of milk and meat meeting in the water is permitted as well as the Maharam that onions aren't sharp.</ref> But many are strict.<ref>Dvar Charif p. 177 citing Yad Yehuda Pirush Haaruch 95:16 arguing that we can't be lenient based on the Shulchan Aruch 95:3 since the Rama disagrees with that completely.</ref>
 
# If an onion was cut with a meat knife and put into a parve soup cooked in a dairy pot that was used within 24 hours for dairy, some say that the pot is permitted and the food shouldn't be eaten with dairy.<ref>Dvar Charif p. 176 Chedrei Deah 96 and Maharil Diskin 14 based on the opinion of Shulchan Aruch 95:3 that nat bar nat of milk and meat meeting in the water is permitted as well as the Maharam that onions aren't sharp.</ref> But many are strict.<ref>Dvar Charif p. 177 citing Yad Yehuda Pirush Haaruch 95:16 arguing that we can't be lenient based on the Shulchan Aruch 95:3 since the Rama disagrees with that completely.</ref>
Line 35: Line 35:
 
#An onion that cut with a meat knife and then cooked in a parve dry dish, such as frying onions with fish, there is a dispute whether the pot is now meat.<ref>according to the Magen Avraham the onion gives off a single taste of meat into the pot, however, according to the Even Haozer the onion gives off the nat bar nat taste into the pot. (He adds the Chavot Daat 122 as well specifically regarding when the onion was cut with a meat knife and not fried in a meat pot.)</ref>
 
#An onion that cut with a meat knife and then cooked in a parve dry dish, such as frying onions with fish, there is a dispute whether the pot is now meat.<ref>according to the Magen Avraham the onion gives off a single taste of meat into the pot, however, according to the Even Haozer the onion gives off the nat bar nat taste into the pot. (He adds the Chavot Daat 122 as well specifically regarding when the onion was cut with a meat knife and not fried in a meat pot.)</ref>
  
===Cut with Dairy Knife and Cooked with a Meat Soup===
+
===Cut with Dairy Knife and Added to a Meat Soup===
 
# If a dairy knife is used to cut an onion and it is then put in a meat food if that meat food is liquidy such as a soup and is sixty times the width of the knife the entire mixture and onion is permitted.<ref>The Shulchan Aruch YD 94:6 writes that if vegetables absorb taste of meat and they are then cooked in a milk pot if it can be ascertained how much meat was absorbed in the vegetables, if in the pot there's sixty times the meat everything is permitted. The Rama explains that we don't say that the meat taste should expand to the size of the vegetables since they are all permitted. Maharam Lublin 28 writes that this principle is also true in a case of an onion cooked with a meat knife that is cooked with milk that if there's sixty times the meat that the knife absorbed in the milk it is permitted. Shach 94:23 codifies this. Rabbi Akiva Eiger 94:7 questions this as Shulchan Aruch implies that only if the food is cooked in a milk pot is the vegetables permitted but not if it is cooked in milk. His reasoning is that once milk is absorbed into the vegetables it becomes forbidden.  </ref>
 
# If a dairy knife is used to cut an onion and it is then put in a meat food if that meat food is liquidy such as a soup and is sixty times the width of the knife the entire mixture and onion is permitted.<ref>The Shulchan Aruch YD 94:6 writes that if vegetables absorb taste of meat and they are then cooked in a milk pot if it can be ascertained how much meat was absorbed in the vegetables, if in the pot there's sixty times the meat everything is permitted. The Rama explains that we don't say that the meat taste should expand to the size of the vegetables since they are all permitted. Maharam Lublin 28 writes that this principle is also true in a case of an onion cooked with a meat knife that is cooked with milk that if there's sixty times the meat that the knife absorbed in the milk it is permitted. Shach 94:23 codifies this. Rabbi Akiva Eiger 94:7 questions this as Shulchan Aruch implies that only if the food is cooked in a milk pot is the vegetables permitted but not if it is cooked in milk. His reasoning is that once milk is absorbed into the vegetables it becomes forbidden.  </ref>
 
===Fried in a Meat Pot and Added to a Parve Soup===
 
===Fried in a Meat Pot and Added to a Parve Soup===

Revision as of 15:26, 8 October 2021

Impact of Sharp Foods

  1. If one cuts a sharp food such as a radish with a meat knife that radish is considered meat and may not be eaten together with dairy.[1]
  2. If one cuts or cooks a sharp food with milk or meat and that food is cooked with other food one needs to nullify the amount of taste in the sharp food. For example, if one cut an onion with a dairy knife and then it was cooked in the chullent, in order to nullify the dairy taste in the onion to permit the chullent one would need sixty times the entire blade of the knife[2], assuming that the blade of the knife is smaller than the onion piece cut.[3]

Examples of Sharp Foods

  1. Examples of sharp foods include: onion[4], garlic[5], horse radish[6], radishes[7], asafoetida[8], leeks[9], lemons, Etrogim[10], salty fish such as herring.[11]
  2. Some liquids are considered a sharp food including: vinegar, lemon juice, distilled spirit (Arak), and borsht.[12]
  3. Spices are considered a sharp food including: pepper, ginger, and salt.[13]
  4. Some say that radishes with a white peel aren't a dvar charif and would be lenient for a great loss but others argue.[14]
  5. Cucumbers, cabbage, apples, pears, and plums aren't sharp foods.[15]
  6. Many say that beets aren't a sharp food.[16]
  7. Foods which aren't explicitly enumerated as a sharp or non-sharp food some poskim say depend on whether they are edible on their own. If they aren't edible because of their sharpness such as a raw onion they are sharp foods and if they are edible but are sharp should initially be treated as a sharp food but after the fact in a case of loss one can be lenient.[17]
  8. Onions that are cooked aren't considered sharp after they are cooked if they are later cut or used in another pot.[18]

Nat Bar Nat

Cooked in a Clean Pot

  1. Even though the pot that was used to cook the sharp food was clean the sharp food still takes on the status of the knife or pot (nat bar nat).[19]

Cut with Clean Knife

  1. Even though the knife was clean that was used to cut the sharp food the sharp food still takes on the status of the knife or pot (nat bar nat).[20]

Cut with Meat Knife and Then Cut with a Dairy Knife

  1. If an onion was first cut with a meat knife and then cut with a dairy knife, the onion is considered to have tastes of meat and milk and can't be eaten. However, there is a dispute whether the second knife needs to be koshered.[21]

Cut with Meat Knife and Cooked or Fried in Dairy Pot

  1. If the sharp food is cut with a meat knife or cooked in a meat pot and then cooked in a dairy pot or with a dairy spatula or utensil the sharp food is considered not kosher as well as the dairy pot, and the spatula or utensil need koshering. This is true even if the dairy pot, spatula, or utensil is eino ben yomo. This is also true of the opposite case, such as a sharp food cut with a dairy knife.[22]
  2. This is also true if the sharp food cut with a meat knife is fried in a dairy pan with some oil.[23]

Cut with Meat Knife and Added to Parve Food

  1. If the sharp food is cut with a meat knife or cooked in a meat pot and then it is cooked with another food, if that second food is mixed with milk there is a dispute if the second food with milk is permitted (nat bar nat bar nat).[24] For a case of need it is permitted.[25]

Cut with Meat Knife and Added to a Parve Soup in Dairy Pot

  1. If an onion was cut with a meat knife and put into a parve soup cooking in a dairy pot that wasn't used within 24 hours for dairy the pot is permitted and the food shouldn't be eaten with dairy.[26]
  2. If an onion was cut with a meat knife and put into a parve soup cooked in a dairy pot that was used within 24 hours for dairy, some say that the pot is permitted and the food shouldn't be eaten with dairy.[27] But many are strict.[28]

Cut with Meat Knife and Added to a Parve Soup in Parve Pot

  1. An onion that was cut with a meat knife and then cooked in a parve soup in a parve pot, the pot remains parve.[29]
  2. An onion that cut with a meat knife and then cooked in a parve dry dish, such as frying onions with fish, there is a dispute whether the pot is now meat.[30]

Cut with Dairy Knife and Added to a Meat Soup

  1. If a dairy knife is used to cut an onion and it is then put in a meat food if that meat food is liquidy such as a soup and is sixty times the width of the knife the entire mixture and onion is permitted.[31]

Fried in a Meat Pot and Added to a Parve Soup

  1. If onions were fried in a meat pot and then added to a soup, that soup should be treated as meat. Even though at this point the onions aren't considered sharp since they finished frying they still have their meat taste from when they were frying in the meat pot. Since they were added to a soup the soup should be considered meat and may not be eaten with milk.[32]
  2. If onions were fried in a meat pot and then added to a soup and then removed from the soup there is a dispute if the soup is considered meat.[33]

Fried in a Meat Pot and Mixed with Dairy Spatula

  1. If onions were fried in a meat pot and after they were finished frying they were mixed with an eino ben yomo dairy spatula, the spatula should be kashered.[34]
  2. If parve liquid that is charif is cooked in a meat pot and then an eino ben yomo dairy spoon is used to mix it, the spoon, liquid, and pot should be treated as non-kosher and kashered.[35]

Fried in a Meat Pot and Mixed with Parve Spatula

  1. If onions were fried in a meat pot and after they were finished frying they were mixed with a parve spatula, the spatula should be treated as meat.[36]
  2. If parve liquid that is charif is cooked in a meat pot and then a parve spoon is used to mix it, the spoon should be treated as meat.[37]

Fried in a Parve Pot and Mixed with Meat Spatula

  1. If parve liquid that is charif is cooked in a parve pot and then a meat spoon is used to mix it, the pot should be treated as meat.[38]

Teyma

  1. If someone cut a sharp food with a meat knife and then tasted it, if it didn't have any meat taste, and then one mistakenly cooked that sharp food with a dairy food one can be lenient after the fact.[39]

Efsher Lsachto

  1. If a sharp food was cut with a meat knife and then was cooked in a dairy food that food is forbidden unless there is sixty times the knife that was used to cut the sharp food. In that case the sharp food itself is permitted.[40]
  2. If a sharp food was cut with a meat knife and then was left soaking in milk, the milk is forbidden unless the milk is sixty times the knife. In that case the sharp food is forbidden and must be removed before having the milk.[41]

Cutting Boards

  1. There is a dispute whether the cutting action that transfers taste to a sharp food includes only the knife or even the cutting board or plate underneath.[42]
  2. Initially one should cut a sharp food with a parve knife on a parve cutting board, or with a meat knife on a meat cutting board, or milk knife and milk cutting board. If someone cut a sharp food with a meat knife on a milk cutting board some say that the food, the knife, and the cutting board are non-kosher but most poskim are lenient after the fact.[43]
  3. After the fact if someone used a parve knife to cut a sharp food on a meat cutting board initially one should only eat that sharp food with meat, however, the knife can still be treated as parve. Similarly, if someone cut with a meat knife on a parve cutting board one should initially eat that sharp food only with meat but the cutting board can still be treated as parve.[44]
  4. If someone cut a very spicy meat that is considered a sharp food on a milk cutting board there is more reason to be concerned and one should ask a Rabbi.[45]

Ein Ben Yomo

  1. There is a dispute if one cuts a sharp food with an eino ben yomo meat knife if the sharp food is considered meat. The halacha is to be strict.[46] Some say this is only rabbinic while most assume it is biblical.[47] Some Sephardim hold that if the meat knife was eino ben yomo when used to cut a parve sharp food the sharp food is still parve.[48]
  2. If someone cooks a parve sharp food in a pot that is eino ben yomo that cooking doesn't make the pot considered as though it is ben yomo.[49]

Sources

  1. Gemara Chullin 111b, Shulchan Aruch YD 96:1
  2. Shulchan Aruch Y.D. 96:1. Badei Hashulchan 96:25 adds that we use the entire blade of the knife and no just the part that cut the onion since it is assumed that people usually use the whole blade. Though the handle isn't included.
  3. Shach 96:9, Maadanei Hashulchan 96:18
  4. "Betzel" Shulchan Aruch 96:2, Laws of Kashrut p. 323
  5. "Shum", Shulchan Aruch 96:2, Laws of Kashrut p. 323
  6. Dvar Charif p. 25
  7. "Tzanon". Aruch Hashulchan 96:13, Badei Hashulchan 96:2
  8. Translation of Chiltit (Google Translate April 7 2019)
  9. "Karti", "Kerishin", Shulchan Aruch 96:2, Dvar Charif p. 27, Laws of Kashrut p. 323
  10. Dvar Charif p. 27
  11. Dvar Charif p. 28
  12. Dvar Charif p. 29
  13. Dvar Charif p. 31
  14. The Aruch Hashulchan 96:13 writes that he heard a gadol say that radishes with a black peel is a dvar charif but not one with a white peel. He concludes that one could rely on this for a great loss. R' Baruch Epstein tells how the Gadol was Rav Chaim Volozhiner in Mekor Baruch (vol. 3 Perek 16 Seif 2 page תקפג), Dvar Charif p. 26 cites the Darkei Teshuva 96:1 who disagrees. Badei Hashulchan 96:2 cites both opinions.
  15. Aruch Hashulchan 96:13
  16. Pri Megadim S"D 96:1 notes that he isn't sure what tradin is. Horah Brurah 96 fnt. 6 writes that tradin and silka isn't beets. He cites the Tiferet Yosef YD 1, and Rav Yosef Kapach (Simchei Hamishna "Tradin"). Instead he defines taradin as Swiss chard. Horah Brurah concludes that beets isn't a dvar charif. (Often tradin is defined as beets e.g. Jastrow p. 997 "Silka"). Aruch Hashulchan 96:13 writes that beets aren't sharp. Badei Hashulchan 96 fnt. 8 cites the Makom Shmuel 90 who says that tradin aren't beets.
  17. Dvar Charif p. 30 citing Maharsham in Daat Torah and others
  18. Dvar Charif p. 38 citing Pitchei Teshuva 96:4
  19. Shulchan Aruch Y.D. 96:1
  20. Shulchan Aruch Y.D. 96:1
  21. The Magen Avraham OC 451:31 holds that the taste from the onion goes from the onion into the second knife and makes it non-kosher. However, the Even Haozer YD 96 argues because it is a case of three nat's, one taste from the meat into the knife, a second from the knife into the onion, and a third from the onion into the second knife. Also, the Chavot Daat 96:6 is lenient since the taste in the onion doesn't taste to the second knife since it is dry and a dry absorption can't forbid a dry utensil. He is only strict if it is a fatty absorption. Pri Megadim MZ 447:13 has a unresolved inquiry about the point of the Chavot Daat. Bet Shlomo YD 1:168 is strict like the Magen Avraham and in this case forbids the second knife.
  22. Dvar Charif 10:13 ch. 185 based on Rama 95:2
  23. Dvar Charif 10:12 ch. 185
  24. Badei Hashulchan 96:5 quotes that the Pri Megadim is strict since we treat nat bar nat of a dvar charif like one nat so too with three nat's. (Commonly this is known as the opinion of the Even Haozer YD 96.) However, Rabbi Akiva Eiger argues.
  25. Badei Hashulchan 96:5
  26. Dvar Charif p. 179 is lenient since it is nat bar nat of hetera in the pot since it is eino ben yomo. Even for the minhag of the Rama 94:5 it isn't necessary to be strict since we can include the opinion that onions aren't charif.
  27. Dvar Charif p. 176 Chedrei Deah 96 and Maharil Diskin 14 based on the opinion of Shulchan Aruch 95:3 that nat bar nat of milk and meat meeting in the water is permitted as well as the Maharam that onions aren't sharp.
  28. Dvar Charif p. 177 citing Yad Yehuda Pirush Haaruch 95:16 arguing that we can't be lenient based on the Shulchan Aruch 95:3 since the Rama disagrees with that completely.
  29. Dvar Charif 10:1. He explains that the taste of meat transferred (1) from the meat to the knife (2) to the onion (3) to the soup (4) to the pot. Even though we look at the nat bar nat of dvar charif as one nat, the taam from the onion is only one taam and then the soup is nat bar nat and the pot is nat bar nat with two kelim which is permitted according to everyone.
  30. according to the Magen Avraham the onion gives off a single taste of meat into the pot, however, according to the Even Haozer the onion gives off the nat bar nat taste into the pot. (He adds the Chavot Daat 122 as well specifically regarding when the onion was cut with a meat knife and not fried in a meat pot.)
  31. The Shulchan Aruch YD 94:6 writes that if vegetables absorb taste of meat and they are then cooked in a milk pot if it can be ascertained how much meat was absorbed in the vegetables, if in the pot there's sixty times the meat everything is permitted. The Rama explains that we don't say that the meat taste should expand to the size of the vegetables since they are all permitted. Maharam Lublin 28 writes that this principle is also true in a case of an onion cooked with a meat knife that is cooked with milk that if there's sixty times the meat that the knife absorbed in the milk it is permitted. Shach 94:23 codifies this. Rabbi Akiva Eiger 94:7 questions this as Shulchan Aruch implies that only if the food is cooked in a milk pot is the vegetables permitted but not if it is cooked in milk. His reasoning is that once milk is absorbed into the vegetables it becomes forbidden.
  32. Dvar Charif 3:6. He cites Yad Yehuda 95:16 and Darkei Teshuva 95:39 but writes that this is obvious.
  33. Dvar Charif ch. 3 fnt. 28 writes that according to those who hold that the onion which accepted meat taste only gives off a weak taste then there is only nat bar nat in the soup. If milk is then mixed into the soup it is still kosher. Or if the soup is reheated in a dairy pot it is still kosher. However, according to the Magen Avraham 451:31 the onion gives off a strong taste (one noten taam). Then the soup is like it was cooked with meat and if milk is added or cooked in a meat pot is a problem. See Dvar Charif 10:1, Shach 95:3, Pri Chadash 95:5, Minchat Yakov 57:3, Chachmat Adam 48:1, Bear Yitzchak YD 8.
  34. Dvar Charif siman 12:2:6 writes that whether the onions which got the taste of the meat from the pot can transfer it to the spatula is a discussion if nat bar nat is a problem when it involves 2 kelim. Here the meat taste went (1) from the meat to the pot, (2) then to the onions, and (3) then to the spatula. Even though we view a nat bar nat of meat in the onions as one taam, still in the spatula it is nat bar nat with 2 kelim. Bottom line, he says that although there's many factors to permit nat bar nat with 2 kelim after the fact, in practice we should be strict to kasher. Certainly the eino ben yomo spatula needs kashering like in the Rama 94:5. Also, the parve spatula doesn't really have that chumra, nonetheless it should be kashered lest it be used in the future for a dvar charif which would bring out a taste of nat bar nat with 2 kelim which isn't permitted initially.
  35. Dvar Charif siman 12:2:6 says that the charif liquid brings out a dairy taste from the spoon and a meat taste from the pot and it is all non-kosher.
  36. Dvar Charif siman 12:2:6
  37. Dvar Charif siman 12:2:6 writes that in theory there's reasons to be lenient since it is nat bar nat with 2 kelim, in practice we're strict so that the parve spoon isn't later used for a dvar charif. The taste is (1) from the meat to the pot, (2) then to the liquid, (3) then to the spoon. Even though the liquid is treated as one taam still the spoon is treated as nat bar nat with 2 kelim. He says that certainly the Magen Avraham would forbid it but his discussion is within the Even Haozer's view.
  38. Dvar Charif siman 12:2:6 writes that in theory there's reasons to be lenient since it is nat bar nat with 2 kelim, in practice we're strict so that the parve spoon isn't later used for a dvar charif. The taste is (1) from the meat to the spoon, (2) then to the liquid, (3) then to the pot. Even though the liquid is treated as one taam still the spoon is treated as nat bar nat with 2 kelim. He says that certainly the Magen Avraham would forbid it but his discussion is within the Even Haozer's view.
  39. Shulchan Aruch 96:1 allows tasting the food even initially, however, the Shach 96:5 argues that it is only permitted after the fact. Badei Hashulchan 96:15 agrees. In the biurim he quotes the Rabbi Akiva Eiger who says that one needs to taste the entire area that is within a fingerbreadth of the cut but is lenient for the Pri Megadim who holds that one could taste any area near the cut if there's another reason to be lenient.
  40. Shach 94:23, Taz 96:5, Magen Avraham 447:38, Pri Megadim E"A 96:8 citing Maharam Lublin 28
  41. Pri Megadim E"A 96:8 explains that soaking food doesn't spread the taste evenly.
  42. Badei Hashulchan 96:7. He concludes to be strict. Sefer Dvar Charif p. 12 discusses this and quotes Rav Elyashiv as holding that initially one should avoid the situation but after the fact there's no issue.
  43. Dvar Charif p. 13
  44. Dvar Charif p. 14
  45. Dvar Charif p. 15
    • Sefer Hatrumah siman 60 holds that if one uses a meat knife to cut an onion the onion is considered meat even if the knife wasn't used within 24 hours for meat. The reason is that since the sharp food draws out a taste more powerfully than other foods it makes the absorption in the wall reinvigorated and taste good even though it was 24 hours. The Tosfot Chullin 111a s.v. agav also suggests this position. The Rambam Maachalot Asurot 9:24 (as understood by Bet Yosef 96:2) argues that a sharp food is only effective if the pot was used within 24 hours.
    • Shulchan Aruch YD 96:1 cites the rishonim who are lenient as long as the knife was eino ben yomo and then quotes the Sefer Hatrumah as some say to be strict. See also Shulchan Aruch YD 96:3, 103:6, and 114:8. Kaf Hachaim 96:11 explains that we're concerned for both opinions. The Rama 96:2-3 is strict for the Sefer Hatrumah as and that is the consensus of Ashkenazic poskim including the Shach 96:6, Aruch Hashulchan 96:4, and Badei Hashulchan 96:20.
    • Bet Meir YD 96:3 writes that we're not concerned after the fact if a sharp food was cut with a meat knife which was eino ben yomo and added to a dairy food or the opposite. His reasoning is that it is two chumrot to say that nat bar nat is treated as one transference of taste and also to say that if it is eino ben yomo we treat it as ben yomo.
  46. Knesset Yechezkel 24 writes that the fact that a dvar charif only reinvigorates eino ben yomo taste is only rabbinic.
  47. Shulchan Aruch YD 96:1 cites the dispute whether a dvar charif can reinvigorate tastes in pots that weren't used within 24 hours. The primary opinion is lenient. This is reiterated in Y.D. 96:3 and O.C. 447:8. However, Shulchan Aruch Y.D. 103:6 quotes an opinion that a dvar charif reinvigorates taste that wasn't used within 24 hours. This is reiterated in YD 114:8. The Peleti 96:5 answers that Shulchan Aruch held that we only assume a dvar charif reinvigorates taste if it originally forbidden, but for something that was originally permitted it doesn't since there is also the factor of nat bar nat. This corroborated by many achronim cited by Yabia Omer 8:43:5 including Eliya Rabba 447:24, Chachmat Adam (Binat Adam Shaar Isur Vheter 48), Pri Megadim M"Z 96:10, Rabbi Akiva Eiger (on Taz 96:16 in first approach), and Knesset Hagedola (hagahot hatur 96:18). Yabia Omer OC 8:43:5, Yalkut Yosef Isur Vheter v. 2 p. 12 and 362, and Horah Brurah 96:11 agree that for eino ben yomo and for heter dvar charif isn't an issue. It is only a problem for when using a prohibited knife or a meat knife to cut something sharp that is dairy.
  48. Shach 95:7 and 122:2 writes that using a dvar charif doesn't reinvigorate the taste in the pot that it should be considered ben yomo. Chachmat Adam 48:16, Chavot Daat 95:8, Pri Chadash 122:2, and Aruch Hashulchan 122:9 agree with the Shach. Nekudat Hakesef the son of the Shach 122 argues with his father. Dvar Charif p. 74 is lenient. He points out that the Magen Avraham 451:31 who holds that even nat bar nat bar nat is forbidden with a dvar charif this too would be forbidden.