1/3 cup balsamic vinegar
1/3 cup olive oil
1/4 cup parsley, minced
2 garlic cloves, crushed
1/2 tsp. salt
1/4 tsp. black pepper, freshly ground
4 tuna steaks, 3/4 inch thick
1 red bell pepper, cut in strips
1 yellow bell pepper, cut in strips
1/2 red onion, cubed

Whisk together vinegar, oil, parsley, garlic, salt and pepper to form
marinade. Place tuna steaks in a suitable container for marinating and
pour marinade over tuna. Cover and refrigerate for 2 to 4 hours. Turn
steaks occasionally.
Prepare grill or broiler. Saute pepper strips and onion in 1 tablespoon
olive oil and 1 tablespoon marinade until tender. Set aside.
Grill steaks for 2 minutes on each side while basting with the marinade.
Tuna should flake apart and be gray-ish in color all the way through.
Place tuna steaks on serving plates and garnish with onion and pepper
strips. Serve.