Thaw fish, if frozen; set aside. In a small bowl, stir together the bread crumbs, onion, the 1/4 cup melted butter, the lemon juice, the 1 tablespoon parsley, the soy sauce, sage, salt, and pepper. Spoon 1 to 2 tablespoons of the bread crumb mixture onto each fish fillet. Roll up fish around stuffing; secure with wooden toothpicks, if necessary. Arrange in a 3-quart rectangular baking dish. Drizzle with the 2 tablespoons melted butter.
Bake in a 350 degree F oven about 30 minutes or until fish just flakes easily when tested with a fork and stuffing is heated through. Sprinkle with additional parsley and serve with lemon wedges. Makes 4 to 6 servings.