Don't be put off by its French name. aking a roux is one of the simplest cooking techniques. This mixture of cooked fat and flour is the basis for cream sauces, homemade macaroni and cheese, soups and gumbo, among others. Creating a roux is about as complicated as making toast, but the constant stirring required for a perfect roux requires a bit more dedication.
To make the beginnings of a light sauce such as a bechamel, butter and white flour are the most traditional choices. Some recipes call for different types of fat. Roux made with bacon fat or vegetable oil will lend your finished dish different flavor than one made with butter. To make a dark roux, used for Cajun or Creole cooking, use butter, oil, bacon fat or drippings left over from cooking meat. Different flour varieties can also be used but will affect the texture and taste of the roux.
No matter what type of fat and flour you're using, a roux always requires that you use equal amounts of them. Start with a sturdy pot or pan, preferably one made of cast iron. Heat the pan over low or medium-low heat and add the butter until it melts, then add the flour. If you're using liquid fat, you can add it and the flour at the same time. Stir the mixture together and keep stirring until your roux reaches your desired doneness.
A basic light roux of butter and flour may only need to cook for one or two minutes, just long enough for the flour to lose its raw taste. Let it cook a few minutes longer and it will start to develop a nutty flavor. To make a medium roux, continue stirring and cooking the mixture until it turns reddish brown. This could take 20 minutes or longer, depending on how much roux you're making. Cooking dark roux until it's the color of dark chocolate could take 40 minutes or longer.
When you're satisfied with the color of your roux, remove it from the hot pan or add other ingredients right away. Left in the hot pan unstirred, the roux can burn. To make a basic creamy sauce, heat milk or broth until it's warm but not hot. Pour this liquid slowly into the roux, whisking the mixture thoroughly to prevent lumps from forming. A gumbo recipe will typically call for onions, vegetables and liquid to be added to a finished roux.