Espagnole sauce, also known as brown sauce, is one of the five mother sauces in classical French cuisine. It is made from a rich brown stock, typically beef or veal, combined with a brown roux, mirepoix (a mix of onions, carrots, and celery), and tomatoes. The sauce is simmered for several hours to develop its deep flavor and color. Espagnole sauce serves as a base for many derivative sauces, such as Bordelaise and Chasseur. It is often used in meat dishes and can enhance the flavor of stews and braises. Its versatility makes it a fundamental component in both traditional and modern cooking.