DIRECTIONS
Preheat grill until briquettes are pure white.
Grease grill well with solid shortening.
Cut tuna into portion sized pieces about 1 to 2-inches thick.
Place the sliced onion on bottom and lay tuna pieces on top.
Pour the dressing over the tuna and let marinate for 10 minutes, then turn over for 10 more minutes.
Place fish on grill, try to avoid pieces touching.
Brush on marinade throughout cooking.
Grill until well seared on one side; turn, baste and cook until tuna is opaque throughout.
Serves 4-5.