Roux (ROO)

A mixture of flour and fat that, after being slowly cooked over low heat,
is used to thicken mixtures such as soups and sauces. There are
three classic roux; white, blond and brown. The color and flavor is
determined by the length of time the mixture is cooked. Both white
roux and blond roux are made with butter. The former is cooked just
until it begins to turn beige and the latter until pale golden. Both are
used to thicken cream and white sauces and light soups. The fuller
flavored brown roux can be made with butter, drippings or pork or 
beef fat. It's cooked to a deep golden brown and used for rich, dark
soups and sauces. CAJUN and CREOLE dishes use a lard-based
roux, which is cooked (sometimes for almost an hour) until a beautiful
mahogany brown. This dark nutty-flavored base is indispensable for
specialties like GUMBO.