Food is used in the game to heal players out of combat, so they can get back to fighting as quickly as possible. When traveling around the world, players will often receive pieces of meat, which, instead of being sold to merchants, could be used to create food.
Food gained through cooking is nearly free and it is actually much more effective than purchasing from a vendor.
Players need to find an NPC who can teach them to Cook. Ask a guard for directions in big cities. These trainers will likely be somewhere near a fire or cooking pot.
Make sure to learn how to create a campfire in order to cook anywhere. Cooks need to carry around flint and tinder along with some simple wood. They can cook over any good fire they find, however, such as a stove, brazier, or fireplace.