In the kitchen, the cooks roasted meats on a spit over the fire. Common foods were stews and potage, a mixture of grains, with or without vegetables and meat, cooked with water until the mix resembled mush. These soups and stews were cooked in clay or iron pots directly in the flames.
In a castle, like the one to which the heroine of my novel, Jeanne of Clairmonde, traveled with the squire, they would have had a portable oven also, but these were luxuries. Bread and other foods were placed inside the oven, then the cook’s helpers buried the oven in the open fire to bake the contents.
The medieval kitchen, especially in homes of the aristocracy, was located a good distance from the Great Hall, where all the entertaining and eating went on. The danger of fire was ever-present in the Middle Ages, in a peasant hovel as well as an aristocrat’s mansion, because cooking was done over an open flame. Thus, if one could afford it, the food was brought in from another building, preferably through a passageway of wood or stone (to avoid the cooling effect of a brisk wind).
A great collection of 14th century recipes, The Forme of Cury, is downloadable, copyright free, from that most awesome of sites, the Gutenberg Project.