Roux

A roux blanc, blond, or brun (white, blond, or brown) is a cooked mixture of equal parts by weight of flour and butter, oil, or any other type of fat. It is considered one of the primary liaisons in making sauces that require medium to long cooking times. A longer cooking time is required for a sauce using a roux to remove the taste of the raw flavor of flour. The different roux are cooked slowly to obtain different degrees of color that will correspond to the final color of the sauce.

Roux can be used hot or cold. The general rule of thumb is that a cold roux is used with a hot liquid, and a hot roux is used with a cold liquid. It is whisked into the liquid, and the more roux that is added, the thicker the sauce will be. When adding the roux to the liquid, it is very important for the liquid to be brought to a boil so that you can verify the proper thickness of the sauce. The quality and gluten content of flour vary from country to country, so the quantity of roux needs to be adjusted to accommodate these differences (120 g of roux will normally thicken 1 liter of liquid).