¼ cup Marsala or red grape juice ¼ cup water ¼ cup sugar ½ teaspoon whole black peppercorns 2 6 inch sprigs fresh rosemary 1 ½ teaspoon balsamic vinegar 1 teaspoon cornstarch 1 ½ teaspoon water ¼ teaspoon lemon juice ¼ teaspoon balsamic vinegar 1 cup fresh blueberries