Combine 1 tablespoon (15 milliliters) finely chopped shallots with 6 tablespoons (90 milliliters) white wine and 6 tablespoons (90 milliliters) mushroom cooking liquid (see Mushroom Essence). Add 1 cup (250 milliliters) demi-glace, ¼ cup (60 milliliters) tomato purée, and 2 tablespoons (30 milliliters) fine, dry duxelles to the sauce. Simmer the sauce for 5 minutes, and finish it with 2 teaspoons (10 milliliters) finely chopped parsley.