Wash and drain scallops and put in flat baking dish. Combine remaining ingredients, except mushrooms, and pour over scallops turning to coat all sides. Marinate in refrigerator several hours. Thread scallops onto skewers alternately with mushroom caps. Place on rack and broil 3 - 4 inches from heat 8 to 10 minutes. Turn and broil 8 to 10 minutes longer. Brush several times with marinade during broiling. Serve with tartar sauce.