In a mixing bowl, combine the soy sauce, olive oil, honey, minced garlic, grated ginger, sesame oil, lime juice, black pepper, and red pepper flakes. Whisk together until well blended. This step ensures that all the flavors meld together, creating a cohesive marinade.

Taste the marinade and adjust seasoning if necessary. You may want to add more honey for sweetness or lime juice for acidity, depending on your preference.

Place the tuna steaks in a shallow dish or a resealable plastic bag. Pour the marinade over the tuna, ensuring each piece is well coated. This allows the flavors to penetrate the fish, enhancing its natural taste.

Cover the dish with plastic wrap or seal the bag, and refrigerate for at least 20 minutes, or up to 2 hours for a stronger flavor. Avoid marinating for too long, as the acidity can start to 'cook' the fish.