The Halacha discusses a case of a pot which was used to cook meat within the last twenty-four hours. Such a pot is designated "Ben Yomo" (within its day), even if it is totally clean. There is still residual meat flavor within the walls of the pot. If one boiled milk in that pot, the meat in the walls is also cooked along with the milk. According to the Kaf HaHaim (Rav Ya’akob Haim Sofer, Baghdad-Israel, 1870-1939) (87:14), this act of boiling the milk constitutes a Torah prohibition of cooking meat and milk together. He holds that this is considered Derech Bishul, a normal way of cooking, and thus the milk becomes Assur B’Hana’ah (forbidden to derive benefit), and may not be given to animals or sold to a non-Jew. This applies to most pots in which there is generally never sixty times its contents relative to the surface area of the pot. Moreover, the pot also becomes forbidden since it absorbed the prohibited mixture of cooked meat and milk, and it now requires koshering with Haga’alah.
