1. Combine marinade ingredients. 2. Place tuna steaks in a flat non-reactive dish or pan. Cover with marinade. Let stand in refrigerator for 1-4 hours, turning often. 3. Preheat grill or broiler. 4. Grill or broil tuna, basting frequently, until medium rare (about 10 minutes per inch of thickness). 5. Alternative preparation: do not marinate fish. Steam the fish steaks, and pour heated marinade over. Let stand for a few minutes before serving.