2,467. Cooking in a Non-Kosher Pot

Maachalos Assuros 17:1

If the meat of a neveila, of a creeping thing or of a swarming thing was cooked in an earthenware pot, one may not cook the meat of a properly slaughtered animal in the same pot on the same day; if one did so, it is prohibited. If he cooked something different in it, it’s prohibited if the prohibited taste is discernable.

Maachalos Assuros 17:2

The Torah only prohibited a pot on the same day because the taste of the fat absorbed in the pot has not yet degraded. Under rabbinic law, such a pot may never be used again. Because of this, one shouldn’t buy used earthenware utensils, like pots and plates, from non-Jews for use with hot food. This is true even if the utensils are coated with lead. If one did buy such a utensil and cook in it on the second day or later, then the food is permitted.