Rinse albacore with cold water; pat dry with paper towels. In small saucepan, melt butter. Add basil, parsley, mustard, lemon juice and salt and pepper to taste. Place albacore in a glass ceramic baking dish; top with 3/4 of the marinade. Marinate in refrigerator at least 30 minutes, turning once. Drain albacore, and discard used marinade. Place on well-greased broiler pan; baste with reserved marinade. Broil 4-5 inches from source of heat for 3 minutes. Albacore should be pink in the center when removed from heat. Transfer to serving platter and sprinkle with lemon peel.