Why chef sonnenschmidt calls the demi-glace sauce?

Chef Sonnenschmidt refers to demi-glace sauce as a "culinary cornerstone" due to its rich flavor and versatility in French cuisine. This classic sauce is a concentrated mixture of equal parts brown stock and sauce espagnole, simmered to achieve a deep, complex taste. Its ability to elevate dishes and serve as a base for other sauces highlights its importance in professional kitchens. Ultimately, demi-glace embodies the artistry and tradition of classical cooking.