This unbound sauce is similar to Sauce Duxelles except that port is used in the sauce base and the mushrooms are cut into julienne. Reduce ½ cup (125 milliliters) port by half. Add 1 cup (250 milliliters) concentrated brown stock (four times) and 2 ounces (50 grams) mushrooms cut into julienne. Reduce or thin the sauce as necessary to adjust its consistency. Finish with 1 tablespoon (15 milliliters) chopped parsley. Adding 1 to 2 teaspoons (5 to 10 milliliters) balsamic vinegar to the sauce at the end will bring up the flavor of the mushrooms.