A lesson in French saucemaking: Demi-glace is made by reducing sauce espagnole, which in turn is an enriched and slightly thickened brown veal stock.
- 1⁄4 lb. bacon, finely chopped
- 1 yellow onion, peeled and chopped
- 1 carrot, peeled and chopped
- 1⁄4 cup flour
- 2 tbsp. tomato paste
- 10 sprigs parsley
- 2 dried bay leaves
- 2 sprigs thyme
- 2 1⁄2 qt. <a href="https://www.saveur.com/article/Recipes/Brown-Veal-Stock">Brown Veal Stock</a>
- Render fat from bacon in a large saucepan over medium-low heat, about 15 minutes. Add onions and carrots and cook, stirring occasionally, for 5 minutes.
- Sprinkle vegetables with flour and continue cooking, stirring occasionally, for 10 minutes. Add tomato paste, parsley, bay leaves, thyme, and 2 quarts of the veal stock. Simmer, skimming occasionally, over medium heat until sauce has reduced by three-quarters, about 3 hours.
- Strain sauce and return to pan. Add remaining 2 cups of the veal stock and simmer over medium heat until sauce has reduced by half, about 2 1⁄2 hours, then strain. Demi-glace can be stored in the refrigerator in a sealed container for up to 1 week or frozen for up to 6 months.