Directions

1. Thaw tuna, if frozen. Rinse fish; pat fish dry with paper towels. Place fish in a resealable plastic bag set in a shallow dish.
2. For pesto marinade: In a small bowl, stir together basil, oil, oregano, thyme, garlic, lemon peel and juice, tangerine peel and juice, salt and pepper. Pour over fish; seal bag and turn to coat fish. Marinate in the refrigerator for 30 to 60 minutes, turning bag once. Remove fish from marinade, reserving marinade. Transfer marinade to a small saucepan. Bring to boiling; reduce heat. Simmer, uncovered, for 1 minute.
3. Lightly grease or coat an unheated grill rack with nonstick cooking spray. For a charcoal grill, grill fish on the greased rack of an uncovered grill directly over medium-hot coals until desired doneness, gently turning and brushing once with remaining marinade halfway through grilling. Allow 5 to 6 minutes or until surface is well-marked and the center is still red for medium-rare and 9 to 12 minutes or until fish flakes when tested with a fork and center of fish is still pink for medium doneness. Discard remaining marinade. (For a gas grill, preheat grill. Reduce heat to medium-hot. Place fish on greased rack directly over heat. Cover; grill to desired doneness as above.)
4. Serve fish with Fennel-Tangerine Salad. Makes 4 servings.