Water vapor
Water vapor is a critical component of how pan frying works. Raw meat products contain up to 73% water. The meat is cooked by the evaporation of this water. When the water is vaporized it leaves the meat through pores in the surface of the meat. Another source of water vapor is the Maillard Reaction. This reaction is responsible for why meat, and many other food products, turn brown when cooked. This reaction only occurs at high temperatures. Water vapor is a byproduct of the Maillard reaction.