Late middle ages, of course, there being a certain paucity of knowledge about the earlier times.
It discusses the sorts of document we do have. Rare account books that record all the purchases of food, in a household where all the food was purchased; normally you raised at least some of it. Butchers' accounts. Recipes, which were more like brief reminders to cooks of things that might slip the mind. Also medical treatises. Not only did they discuss what foods were hot or cold and moist or dry, they discussed how to alleviate these humor imbalances in the cooking process. Most vegetables were dry, coming from earth as they did, and so were boiled; onions were moist and should be fried; fruits were moist and should be roasted. Which also feed their liking for chopping fine and mixing ingredients.
Techniques of preservation. The Lenten rules. Fancies such as sewing together the front half of a rooster and the back half of a piglet -- or mounting the rooster on the piglet and giving it a helmet and lance to make all clear. Beverages. The hall and the manners.
An extensive look