Interesting question... I haven't had to deal with this till now, but I think I would try to derive it from climate to crops, plus technology for preservation, plus trade for foods from other climates, and that would give me my ingredients list.

Then I would try to derive cooking style from culture -- are there people (or technologies) who can keep an eye on a long, slow cooking process, or are we looking for cook-and-serve-fast? Are people eating in big groups or small groups or alone? Is sensual pleasure sought or distrusted or both? How in touch is their lifestyle with seasonality? Is there a single staple crop that has to be changed up? How much of their total income are characters spending on food?

Then I would probably try to do the opposite of one or two common fantasy tropes (waybread, we're looking at you), and call it good.