1. Preheat stove top or gas grill to high heat. Stir together butter, onion, and dill in small bowl. Brush tuna steaks with olive oil and coat with cracked pepper.
2. Place tuna steaks on grill and cook to desired doneness, turning once: 2 min. on each side for rare center; 3-5 min. each side for medium center; 5-6 min. each side for well-done center. Serve topped with a dollop of dill-onion butter.
* Recipe Courtesy of Florida Department of Agriculture Bureau of Seafood and Aquaculture.