In a medium bowl, whisk together the soy sauce, orange juice, lime juice, honey, sesame oil, garlic, ginger, and black pepper until well combined.
Place the tuna steaks in a shallow dish or a resealable plastic bag and pour the marinade over the fish. Ensure the tuna is well coated. Cover the dish or seal the bag and refrigerate for at least 30 minutes, or up to 2 hours for more flavor.
Preheat your grill to medium-high heat.
Remove the tuna from the marinade and discard the marinade.
Grill the tuna steaks for about 2-3 minutes on each side for medium-rare, or longer if you prefer them more cooked.
Once cooked to your liking, remove the steaks from the grill and let them rest for a few minutes.
Slice the tuna steaks and serve garnished with chopped green onions and sesame seeds, if desired.