Dear Rabbi, I used a vinegar/water solution to clean my kettle. I then realized, that the vinegar has no Hechsher and according to the OU and others, since vinegar is a Dvar Charif and it may come from wine, it can be a Kashrus concern, especially if it’s not from the US (this one is from Asia). How do I go about Kashering the kettle? I assume that I can simply boil water in it, my question is whether the entire kettle needs to be filled and let the water over-boil? Or can I just fill to the same level as the vinegar/water solution and only Kasher the area that came in contact with the vinegar? Thank you very much!

Shalom, Thank you for your question. You raise a very interesting point – when we know for certain that only a portion of a vessel was used for non kosher foods, do we need to kosher the entire vessel or is it enough to kosher that part that was used for the non kosher food? This question (called in hebrew “cham be'mizkzat cham kulo”) is debated by all the early codifiers. There are several issues involved – including for example, what the vessel is made of. In short, the practice advised today by the halacha is to kosher the entire vessel (See Shulchan Aruch, Yoreh De'ah, 121, 6 – the Rema, Shach and Taz ibid). Therefore in your case you should boil the kettle over after it is completely full to the top. (Because of this argument, if someone koshered only the part of the vessel they knew to have been used for non-kosher foods, after the fact sometimes we rule that the vessel is now kosher, and a person should approach a Rabbi with their particular situation should it arise). Blessings.