Preheat broiler or start grill.
In a small bowl combine sherry, ginger, soy sauce, honey, maple syrup, garlic, sesame oil, and cilantro. Set aside.
Wash and pat dry tuna steaks. Place in a shallow glass baking dish. Pour sauce over steaks. Let marinate 10 minutes.
Remove steaks from marinade and broil or grill. Cook 5 to 8 minutes on each side, turning once, and basting with marinade. Serve hot.