Since it seems a topic of debate, I would also leave milk out. Milk as a beverage was probably only served fresh from the source, and I'm guessing this only took place in private residences, whether that was a farm house or a dining hall where servants would bring it in. So, if your focus is taverns and so forth, processed foods such as cheese, yogurt, and butter are more likely. Liquid milk would just not be transported very far from the animal it came from.
But I would definitely add the meat of cliff racers and guars, cliffracers as a game animal and guars as both game and domesticated cattle. Alit flesh would probably be poisonous and kigouti flesh would be very rare, for instance in Africa they will sometimes eat a lion if they kill one when it attacks their cows. But they do not go hunting for them, because they are dangerous predators, rather than a typical food source. You could, however, have something like kigouti spleen as a rare expensive ingredient, like rhino horn or tiger [censored].
I guess I would also focus not so much on the ingredients but how they are combined in certain areas, and what kind of effects that has, as in-game that is how alchemy works. For instance, in Balmora perhaps they serve mudcrab with saltrice, but in Seyda Neen they serve it with marshmerrow. In Aldruhn, they don't even have mudcrabs, so they serve saltrice with scrib. There would be some universal stuff (the cheapest, easiest to grow and transport) some local stuff, some imported stuff (near Imperial settlements, forts, trade hubs)
I would also make some races not able to eat some foods. For instance, perhaps kajhiit can not eat leafier plants (herbs are good) but can eat raw meat with no ill effects. Do they include that in Necessities of Morrowind? Or even just lesser bonuses. Let's say Imperials aren't used to eating scrib jelly, so they only get a small bonus, whereas typical bread is more to their palate, and gives full benefits.