Hi friend,

What exactly do you mean by medieval islamic diet? There isn't really such a thing as a standard 'Muslim' diet, nor 'Christian' diet.

Muslims and Christians - both then in the past and also now - live and operate in many different cultures, climates, and countries. The typical diet would reflect one's social standing, and importantly, the immediate environment in which they lived. Certain legal considerations eliminate some types of foods - generally speaking - for both Muslims and Christians, but the vast majority of pre-modern diets consisted of what was locally available to the peoples. And the answer would differ depending on who you asked and from which geographical area you looked at. For eg, some Sufi groups encouraged minimising meat consumption, excessive fasting, and so on, though this would not reflect the specific eating habits of different acetic groups in other parts of the Muslim world, nor the average person in say Mamluk Egypt or Buyid Baghdad

There are, however, some interesting medieval arabic cookbooks that have survived. Some written as family cookbooks, just notes that have survived in manuscript form, and so on. I know of some from Mamluk Egypt and other parts of Syria, but there would be many. Worth having a look there and reading the literature surrounding those texts.

Just an aside whilst I'm in a good mood this evening: interestingly, a lot of the legal schools that were big on sea-food ended up being the dominate legal tradition in most of the coastal areas. Eg The Malikis prominence throughout Spain, Portugal, and some parts of Italy, as well as North Africa and much of the Gulf, historically. Same can be said for the Shafi'is, who like the Malikis have little restriction on sea-food consumption. They tend to occupy the Islands of Indonesia as well as the East African coastline. Hanafis, by contrast, were far more stringent on sea-food consumption, and historically they dominated land-locked regions like Central Asia, Pakistan, Afghanistan and also India to an extent. Obviously the demographics shifted a bit throughout the centuries. It goes without saying that this would be more incidental than anything intentional. Eg, it was Yemeni Muslim traders (who were Shafi'i) who travelled to Indonesia and the people responded by accepting Islam; it wasn't as if they all sat down to decide which Madhhab or school of law was more conducive to the local cuisine.

Hope that is of some help.