Combine first four ingredients. Arrange tuna steaks in shallow glass dish; pour pineapple juice mixture over steaks. Cover and refrigerate for at least one hour. Meanwhile, combine remaining ingredients in a medium bowl; stir gently. Cover and refrigerate until needed. Coat a grill rack with vegetable cooking spray. Remove tuna from marinade and place on grill 4 to 5 inches above medium-hot coals (discard marinade). Grill just until fish begins to flake easily when tested with a fork, allowing about 10 minutes per inch of thickness, turning once during cooking. Serve at once with fruit salsa.
