1In medium microwavable bowl, mix all salsa ingredients. Microwave on High 1 1/2 to 2 minutes, stirring once, until thoroughly heated. Cover to keep warm.
2Set oven to broil. Spray broiler pan rack with cooking spray.
3Mix brown sugar and lime juice in small bowl. Arrange tuna steaks on rack in broiler pan. Brush with brown sugar mixture.
4Broil with tops 4 to 6 inches from heat 4 to 5 minutes on each side or until fish flakes easily with fork, brushing occasionally with brown sugar mixture. Serve fish with salsa.