The first delicatessen generated in the game will always stock food aligned with whatever food-related conducts you have kept up until that point, except for foodless, in which case it stocks only decadent food to tempt you into breaking it.

Tins of “pureed monster” or “soup made from monster” do not break foodless conduct. Possibly change tin behavior so the preparation method can be discerned before eating it, or just display the preparation when the tin is opened, e.g. “You succeed in opening the tin. It contains a puree that smells like newts. Eat it?” This doesn’t have to reveal every preparation method, so that greasy fried food remains a danger.