Sharp Awareness in the Kitchen

Published Spring 2011

I. Davar Charif

On one of my first visits to a food production facility, I cried. Not because I discovered a gross kashrus violation, chalilah; and not from tears of joy over the privilege to promote the availability of kosher food. My tears flowed because at one end of the enormous fruit and vegetable processing factory, the deafening machinery was slicing and packaging – onions! Despite a distance of a few hundred feet from the onion production line, my lachrymal glands were working hard to flush out sulfuric acid from my eyes. Only veteran workers were immune to the effects of the intruding irritants permeating the air.

The same property that makes slicing onions so annoying is also responsible for the pungent flavor and aroma, which have endowed them with culinary popularity for millennia. The Chumash (B’midbar 11:5) enumerates onions as one of the five vegetables the Jews were fond of eating while still enslaved in Egypt.1 During the Middle Ages, before the discovery of the New World, onions were among the three main vegetables of European cuisine, along with beans and cabbage.2 Today, onion growing and processing is a multi-billion dollar industry. This explains why the large factory I visited had an entire section dedicated to slicing and packaging pre-measured amounts of onion slices for fast-food restaurants.

Halacha also recognizes the unique pungency of onions and accords them a special status of davar charif, literally ‘a sharp item’. Other common foods with this classification are radishes, garlic, lemons, hot peppers, spicy pickles and very salty foods.3  These items must be treated with extra caution in a kosher kitchen because, as we will see, they present potential kashrus pitfalls.

II. Exception to the Rule

Generally, the result of a kashrus mishap in the kitchen is mitigated when the surface of the offending utensil is clean and the contact was made below the temperature of yad soledos bo (at least 120oF). A Rav can often advise how to correct the situation with minimal losses. However, when a davar charif is involved, the equation changes and the repercussions are more serious. 4

For example, if one uses a fleishig knife to slice an onion, even if the knife was clean from any prior residue or grease5and the onion was cold, the onion will adopt a fleishig status. The reason for this atypical stringency is because the confluence of the sharpness of the onion, together with the concentrated pressure from the knife blade (duchka d’sakinah), imparts the absorbed meat taste from inside the knife into the onion.6

How much of the onion became ‘fleishig’? The Rema7 rules that due to its sharpness, the entire onion becomes saturated with meat flavor and none of it may be used with dairy. He concedes that, b’dieved, if the onion was inadvertently added to a dairy soup, we may assume that the meat taste penetrated only a k’dei netilah, approximately one inch around where the cut was made. Therefore, the soup would be permitted if it contains sixty times the volume of that area of the onion.8

The stringencies applied to a davar charif entail other halachic anomalies. The Talmud9 teaches that an absorbed taste inside a utensil becomes stale if it remains dormant for more than 24 hours (eino ben-yomo). Subsequently, that taste will no longer prohibit a food that it enters. This is based on the principle of nosein ta’am lifgam, that an adverse infusion of taste cannot create a prohibition. For example, if a pot was used to cook meat and more than 24 hours later it was accidently10 used to cook milk, the milk is permitted. However, this rule is suspended for a davar charif.11 The sharpness of the food rejuvenates any stale taste (whether meat, milk, or non-kosher) embedded in the walls of a utensil, and can have an effect even after 24 hours have elapsed.12

Underscoring this entire matter is the assumption that davar charif  defies yet another standard rule of kashrus, known by its acronym nat-bar-nat.13 The Talmud14 describes a case where hot meat was served on a plate, rendering the plate fleishig. Steaming fish was then served on that same plate. The halacha states that the hot fish is only able to extract a minimal amount of meat taste from the plate, and one is still permitted to eat that fish together with cheese or milk.15 Nevertheless, when a davar charif extracts a meat taste from a knife, its sharpness causes the full potency to be absorbed; consequently, it may not be consumed together with a milk product.

III. Further Applications

A cold taste transfer may occur with any utensil that applies concentrated pressure, not just a knife as in our previous example.  For instance, if the prongs of a milchig fork are inserted into a spicy pickle, the pickle would then be considered dairy and could not be added to a meat sandwich. Food processor or blender blades are also examples of duchka d’sakina.

Furthermore, davar charif is not limited to imparting tastes into food; it can also impart a taste into a utensil. One scenario would be when a mixture of meat and sharp spices is being chopped with a blade. The sharpness of the spices combined with the pressure of the blade will cause the meat taste to become absorbed into the chopper.16

This stringency is also relevant to cutting boards. The Chochmas Odom17 discusses cutting a piece of salty herring (a davar charif)  on a non-kosher plate. He states that the combination of the sharp taste and the pressure from the blade will draw absorbed issur out from the plate and impart it into the fish. Similarly, Rav Shlomo Kluger18 writes that if an onion was cut with a fleishig knife on top of a milchig plate, both the onion and the knife will absorb a combination of meat and milk tastes, thus rendering them both non-kosher.19

For all the above reasons, it is prudent for a kosher kitchen to maintain a pareve knife and cutting board for cutting a davar charif, in order to avoid inevitable mix-ups.

IV. How Fleishig Is It?

If someone eats an onion that became fleishig through a cold taste transfer from a knife, is he then required to wait six hours (or whatever his custom is) before consuming dairy? Poskim say the answer is no.20 Although the onion is considered to be fleishig, to the extent that it may not be eaten with milk, no waiting time is necessary before eating dairy food.

The reverse situation is a matter of dispute. Some Poskim21do not allow consuming an onion that was cut with a milchig knife within six hours of eating meat. Other Poskim permit this.22

V. How Far Does It Travel?

To what extent does an absorbed taste travel when transported through the medium of a davar charif?  Consider a case where an onion was sliced with a fleishig knife and then chopped inside a pareve food processor.  The Magen Avraham23 rules that since the onion is a davar charif and contains a full absorption of meat taste, it will render the blades of the food processor ‘fleishig’. Taking this further, if these blades were then used to chop a second onion, that onion would also become ‘fleishig’ and may not be eaten with dairy. If a third onion was cut with a milchig knife and chopped in the same food processor, the blades have now absorbed basar v’chalav and may not be used until they are kashered.

Even HaOzer disagrees and holds that b’dieved, when the food processor was used for a second onion, we may assume that the meat taste from  the first onion did not compromise the pareve status of the blades.24 Contemporary poskim follow this leniency when necessary.25 However, Even HaOzer himself concedes that ideally the blades should be kashered prior to using them for pareve items.

IV. Fish and Onions

Based on a statement in the Talmud,26 widespread practice is to avoid cooking or eating fish together with meat (including fowl) due to concern that this may cause illness. May one add onions that were sliced with a fleishig knife to a dish of fish?

This question relates to another issue: May one cook fish in a pot that was previously used to cook meat? Since actual meat is not being combined with the fish (only meat taste expelled from the walls of the pot), there should be no problem provided the pot is clean from any meat residue.27 However, many follow an ancient custom recorded in the Tur (13th-14th centuries) to be strict and use a dedicated fish pot. It is reasonable to suggest that one’s conduct regarding the meat pot should determine how to treat a davar charif that was cut with a meat knife. Some suggest that even those who are lenient with regard to the pot should be strict with regard to adding a davar charif.28

V. Are Onions Always Sharp?

All onions are not created equal. There are many varieties, each with its own characteristics.
Red onions are milder; among yellow and white onions, the Vidalia, Spanish, Bermuda, Walla Walla, and White Crystal Wax are less bitter. The degree of pungency is also a product of other factors, such as growing and storage environments.29  Are they all classified as davar charif, or are there some exceptions?

The Shulchan Aruch does not differentiate between different varieties of onions. Later poskim acknowledge scenarios when they are not considered charif. Pischei Teshuva30 notes that while onions are still small, they are mild and have not yet attained the status of a davar charif; therefore, he is lenient if the knife was not a ben-yomo. Kaf HaChaim31emphasizes that this leniency is limited to onions that are immature, but varieties of onions that are naturally small are certainly considered charif.32

Another factor is that onions and other devarim charifim often lose their sharp quality after some processing.  This fact is readily supported by observing an onion fried in oil, baked into a kugel, or cooked in a soup. Homemakers with sensitive eyes know that peeling and chilling an onion before cutting it will also dull its sharpness.33 Based on the item and the method of cooking, a competent Posek can determine at what point a davar charif is no longer considered sharp.34

A more general leniency to this entire topic is found in the Beis Meir (glosses to Y.D. 96:3). As mentioned above, a davar charif supersedes the usual dinim of eino ben-yomo and nat-bar-nat. The Beis Meir proposes that these stringencies are compounded only in the case of a tznon, radish, the sharp item mentioned explicitly in the Talmud. However, one may be lenient with regard to other seemingly sharp vegetables provided that there is doubt as to whether or not the blade absorbed meat or dairy within the previous 24 hours. Some Poskim will utilize this ruling in the event a mistake occurs.35

More than separating the meat from the milk, keeping a kosher home requires vigilance for issues that pertain to a davar charif. This discussion should encourage us to maintain ‘sharpness’ in the kitchen, and enable us to properly present the issues to a Posek should any problems arise.


Overnight Onions

Overnight Onions:
 The Talmud36 teaches that one puts himself in a serious danger from ruach ra’ah if he eats onions, garlic cloves, or eggs that were left peeled overnight. The danger exists even if they are wrapped in a cloth or enclosed in some other way. To block the ruach ra’ah, some of the peel – even a minute amount – must remain attached. It is enough to just leave the hairy strands on top of the onion.37

Kaf HaChaim38 observes that people do not refrain from eating salads or other dishes that contain peeled onions and garlic, even though the salads were left overnight. He suggests that the concern applies only when these items are alone, but not when they are mixed with other ingredients.39 Divrei Yatziv40 says it is sufficient to just sprinkle enough salt to impart a salty taste; likewise, an onion sautéed in oil is not a problem.

Today, kashrus agencies certify processed foods such as onion/garlic powder, peeled garlic, pasteurized/ frozen egg products, and even buckets of hard-boiled eggs. They utilize the ruling of Rav Moshe Feinstein zt”l41 who held that the danger described by the Talmud does not exist when produced in a large scale industrial setting.

1.Chizkuni comments that the onions were not eaten raw, rather they were used to add flavor to cooked meat. Indeed, ancient Egyptians treated onions with sanctity; they took oaths while holding an onion, and onions were entombed together with the pharaohs.


3. Shach 96:18 includes salt as a davar charif.

4. The halochos of davar charif are found primarily in Yoreh De’ah, siman 96, based on Chullin 111b – 112a.

5. The cases described in this article assume that all blades are clean. When they contain residue or grease, the halacha is more strict.

6. One opinion in Tosafos (Chullin 8b, in the name of Rivan) holds that concentrated pressure from a clean knife can create an absorption even into a cold non-davar charif. The halacha does not follow this view. Nevertheless, Poskim record a commendable minhag to always use a dedicated pareve knife when slicing bread. (Aruch HaShulchan 89:16, citing Pri Chadash)

7. Y.D. 96:1

8. Alternatively, if a k’dei netilah around the area of the cut was removed prior to the addition of the onion to the dairy soup, the soup is permitted even without shishim. (Badei HaShulchan 96:32)

9. Avodah Zarah 67b

10. There is a specific Rabbinic enactment against doing this on purpose. Avodah Zarah 76a

11. Rema Y.D. 96:3, Shach #3. Also one opinion in the Mechaber 96:1. Pischei Teshuva 95:4 discusses if this is Biblical or Rabbinical in nature.

12. See Y.D. 103:6. Even in the absence of duchka d’sakinah, this property of davar charif still pertains. For example, borsht with high vinegar content is considered sharp. Therefore, if it was cooked in a meat (or milk, or non-kosher) pot, even if the pot was unused for 24 hours, the borsht is fleishig based on the principle of rejuvenating taste. See later note #34.

13. Nosein Ta’am Bar Nosein Ta’am

14. Chullin 111b

15. This leniency has many limitations. For instance, it only applies when the initial absorption is intrinsically permitted (heteira), such as a kosher meat taste. But if the taste absorbed in the plate is non-kosher, it will carry over to all further hot foods, rendering them all prohibited.

16. See Badei HaShulchan: Tziyonim 96:155

17. Y.D. 56:2

18. Tuv Ta’am V’Daas 3:215. See also Kitzur of Rav Pfeifer 8:2:7.

19. A dissenting opinion is found in ‘Sefer Yehoshua’, by Rav Heshel Bavad, P’sokim 122.  See also sefer Davar Charif’ by Rav Dinkel (1:13, note 57), who quotes Rav Elyashiv as ruling leniently in a b’dieved situation. In the event a davar charif is cut on a non-pareve surface, a moreh hora’ah should be consulted.

20. Based on Rabbi Akiva Eiger, glosses to Y.D. 89, on Shach number 19.

21. P’ri Megadim, O.C. 494, A.A. 6. This is especially so if the knife was known to be a ben yomo.

22. Darkei Teshuva 86:42; Kitzur of Rav Pfeifer 8:2:7 says this is the minhag. This position holds that it is no different than eating food cooked in a ben-yomo milchig pot within 6 hours of eating meat which Rav Aharon Kotler told Rav Heinemann is permitted.

23. Magen Avraham (451:31); Chochmas Odom (49:10) concurs with this position.

24. Even HaOzer, glosses to Y.D. 96:4. He reasons that although a davar charif has the capacity to draw out the full taste absorbed inside a utensil (thereby mitigating the leniency of nat-bar-nat), it is unable to impart a full taste into a second utensil. Thus, the blades will remain pareve. Chavas Da’as 96:6 concurs.

25. See Badei HaShulchan 96:56

26. Pesachim 76b, Shulchan Aruch Y.D. 116:2

27. Even if the pot would be a ben yomo, the meat taste emitted would not generate a sakanah. See Taz Y.D. 95:3.

28. SeferDavar Charif’ (15:6), records in the name of Rav Chaim Kanievsky that in the house of his father, the Steipler Gaon, they cut the onions for fish with a dedicated knife. Unlike a pot, a davar charif absorbs a full taste and is an exception to the rule of nat-bar-nat.

29. See

30. Y.D. 96:3

31. Y.D. 96:3

32. Rav Tzvi Pesach Frank, Mikra’ei Kodesh, Pesach, I:80:3, suggests that some varieties of onions are not charif at all.

33. See Pischei Teshuva 96:4 who brings that Chazal themselves used empirical methods to determine the halachos of davar charif. See also Badei HaShulchan 96:46.

34. Thus, if an onion that is fried in a non-ben yomo fleishig pan becomes hot (yad soledos bo) before losing its sharpness, the stale meat absorption will be rejuvenated and the onion is now fleishig.  But if the onion lost its sharpness prior to becoming hot then it can still be deemed pareve.

35. Albeit, the Darkei Teshuva (96:62) cites the Mishmeres Shalom who is hesitant to apply the leniency of the Beis Meir, except in the exact circumstances that he was discussing, i.e. where an onion was cut with a milchig knife that is assumed to be an eino ben-yomo. This is opposed to a fleishig knife, which is more likely to have been used for hot food.

36. Niddah 17a. It is prohibited for a person to submit himself to a dangerous situation. See Rambam, Hilchos Rotze’ach u’Shmiras HaNefesh, chapter 11; Shulchan Aruch Y.D. 116. The Talmud (Chullin 10a) remarks that dangers to health are dealt with more severely than prohibitions.

37. Semak (4:171) countenances the practice of some people to ward off ruach ra’ah  by replacing the garlic peel even after it was once removed. Divrei Yatziv (Y.D. 31:14, the Klausenberger Rebbe) says that this is not the accepted minhag.

38. Y.D. 116:92, quoting Zivchei Tzedek 116:61.

39. Alternatively, he invokes the position of Maharshal (Yam Shel Shlomo: Kol HaBasar 12) who maintains that the ruach ra’ah of Talmudic times is not prevalent nowadays. This is similar to the statement of Tosafos (Yoma 77b), that certain types of ruach ra’ah no longer exist in parts of the world. (See also Magen Avraham 173.) These halachos are omitted from Shulchan Aruch (see Shevet HaLevi 6:115:5 who sees this as a justification for leniency), but the consensus among Poskim is that this is not sufficient evidence to allow one to place himself in a potentially dangerous situation. (See Chofetz Chaim, Likutei Halachos, Niddah ad. loc.)

40. Y.D. 31:14

41. Iggros Moshe, Y.D. 3:20