Roux refers to a mixture of flour and fat used to thicken sauces , soups, and stews. Though usually made with butter, Rouxs are also made with bacon or poultry fats, margarine, and vegetable oil. The mixture is cooked for a brief time to remove the raw taste of the starch from the flour. Longer cooking results in a darker color, which is favorable in Creole cooking where Rouxs are cooked for long periods until they reach a dark brown color.