Snar the cook in the Jerral View Lodge in Bruma mentions that Skyrim cusine is all about "fresh, simple, big helpings" without actually saying what that includes. It got me wondering what the various folks around the map actually prefer.

I assume they like tomatoes, cheese and wine (and baked goods) in Skingrad, or they wouldn't produce so much. Everyone has a lot of Garlic there, but do they eat it?

The West Weald is the place where wild berries (strawberries and blackberries) grow, so I'd expect Anvil and Kvatch to have some specialities there, but I haven't noticed any.

But what about the other places? Fish and Mudcrabs should be part of the coastal towns' fare, but they don't really appear as food.

Is there a "Beer, Ale and Mead in the North, Wine in the South" thing going? Do the grains - corn, rice, wheat have any geographic associations, or do they grow and eat them equally everywhere?

As you might know, the existing variety of foods in the game doesn't imply that other foods don't exist. I'd consider the game to be an oversimplification of the "true condition" of Cyrodiil. I mean, if you look at the number of existing farms, these would hardly -if not impossible- able to fed every citizens and guards. The only major existing plantations are on Skingrad and, to a lesser degree, Aleswell (which also happened to have "visibility problem").

However, if we were now to discuss "true condition" as opposed to "game condition" then we can start by gathering information from one of the most popular NPC rumors:

This piece of information gave clue about the main locations of farms (plantations, animal herdings, etc) which primarily existed on the eastern part of Cyrodiil (without including Skingrad). The settlements on the eastern part of Cyrodiil like Cheydinhal are most likely to have wider variety of locally grown foods; carrot, corn, radish, tomato, etc. In Cheydinhal, one can assume that given its strong Dunmer influence, there would be some locally-made Dunmer cuisines and imported Morrowind foods, something like Hackle-lo Leaf, Scrib Jerky, and Hound meat.

Next, we can gather next piece of information from the http://www.uesp.net/wiki/Oblivion:Ingredient_Locations and compare them to their correspondence location in Cyrodiil. Although probably not 100% accurate, we can assume that foods or ingredients that exist more in some locations indicate the particular flavoured of foods on the certain regions.