What is the purpose of a roux in cooking?

The purpose of a roux in cooking is primarily to thicken sauces and soups. A roux is a mixture of equal parts flour and fat, typically butter, that is cooked together. The cooking process allows the flour to release starches, which, when combined with liquids in a soup or sauce, help to create a smooth and stable texture. This makes the dish more appealing and gives it body, turning a thin liquid into a creamy consistency.

While roux may have a subtle impact on the flavor and color of dishes, its main function is to serve as a thickening agent. This foundational technique is widely used in classic cuisines such as French cooking, where it's often a base for sauces like béchamel and velouté.