A roux is simply a mixture of fat and flour, generally in equal proportions, combined in a heavy skillet and browned slowly over medium heat to a deep rich flavor and color. Any type fat may be used; oil, butter, butter, shortening, or lard.

The secret of a good roux is constant stirring, which prevents the mixture from burning, until the desired color is reached. A roux requires 15 to 30 minutes to cook to the color of dark chocolate.