Translation:Shulchan Aruch/Yoreh Deah/93
Seif 1: One should not cook dairy in a vessel in which one has cooked meat. If one cooks in it within 24 hours [of cooking the other kind of food], it is forbidden where there is enough to give taste. However, if one waits for 24 hours before one cooks in it – it is a case of giving it [the food] a disgusting taste, and the cooked dish is permitted. As for the vessel, it is forbidden to cook in it both meat and also dairy. {Rama: but for any other food [a parve food], it is permitted. The rule for the lid of the vessel is like the rule for the vessel itself. And there are those who are especially stringent about the lid saying that even though it was not used in the past day, the rule for it is as if it had been used in the past day, and thus they conduct themselves in some places. And thus I do because it is the custom, but it is a stringency without reason. And in any event, in a situation where there is any side [of an argument] to permit without this [leniency of treating the lid like the pot], or where it is necessary for Shabbat or to prevent loss, it is permitted if the lid was not used in the past day, like for the vessel itself. And if they took a lid from a boiling vessel of meat and they put it on a vessel of dairy, if the both of them [the pot and the lid] are hot, the both of them are forbidden if there is food in the vessel of meat and dairy. And if the lid is cold, and the vessel is hot, also the both of them are forbidden if the vessel began to steam under the lid, for the lower one determines. If the lid was hot and the vessel was cold, everything is permitted, except that the food must be peeled if it is possible to peel , and if not, everything is permitted. And if there was not food in the vessel, everything is permitted – it is a case of two vessels that touch each other.}