The foods are amazing and flavorful, not at all what I expected. I have limited my interests to Europe and the Mideast, but still am surprised by the variety of foods and flavors.
There are plenty of books with medieval recipes, with varying degrees of accuracy, what I really love is redacting the original* recipes myself. It's a funny thing that 5 people can read the same recipe and come up with 5 very different dishes. This amazes and inspires me to create dishes as well redact medieval ones.
Creating is a lot harder than redacting. You have to be aware of the cooking methods used in the time and location you are trying to recreate, as welll as which foods were available. "Food" by Waverly Root is an excellent resource.
Resources used (and how annotated):