To make demi-glace, the brown stock is first reduced by half over low heat. This process concentrates the flavors and darkens the color of the sauce. Once the stock has been reduced, it is strained and then thickened with a roux. A roux is a mixture of equal parts flour and fat (usually butter) that is cooked together until it forms a paste. The roux is added to the stock and whisked until it is fully incorporated. The sauce is then simmered for several minutes to cook the roux and allow the flavors to meld together.
Demi-glace is a versatile sauce that can be used in many different dishes. It is often used as a base for other sauces, such as red wine sauce, mushroom sauce, and peppercorn sauce. Demi-glace can also be used to add flavor to soups, stews, and braised meats.
Demi-glace is a delicious and flavorful sauce that can enhance the taste of many different dishes. It is a staple in French cuisine and is sure to impress your guests.