Rinse steaks thoroughly in cold water; pat dry, and place in a 13- x 9- x 2-inch baking dish.
Combine 1/2 cup butter, sherry, lemon juice, soy sauce, dill weed, garlic, and salt in a small bowl; stir well, and pour over steaks. Cover; marinate at room temperature 30 minutes, turning steaks once.
Remove steaks from marinade; reserve marinade. Grill steaks 4 inches from hot coals 10 minutes on each side or until fish flakes easily when tested with a fork, basting frequently with reserved marinade.
Transfer steaks to a warm serving platter, and pour 2 tablespoons melted butter over fish. Garnish with parsley and lemon.