Onions Cut with a Fleishig Knife

I cut onions with a fleishig knife, and then added the onions to a cheese omelet cooking in a dairy pan. I hadn’t used the knife for 24 hours. What should I do?

The omelet should not be eaten, and the pan will need to be kashered. The concept of nosein ta’am bar nosein ta’am (a secondary transfer of flavor) does not apply to a case in which a davar charif, a sharp food such as an onion, was prepared with a fleishig (or milchig) utensil (Rama, Y.D. 95:2). The combination of a davar charif and the pressure of the knife combine to draw out the full flavor of meat (or milk) from the knife and not just a secondary weak flavor (i.e. nosein ta’am bar nosein ta’am).

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