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 thick consistency. This versatile 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, gravies, and braises, making it a fundamental component in traditional cooking.