Build your marinade first. In a shallow dish or large zip-lock bag, whisk together the soy sauce, sesame oil, lime juice, lemon juice, minced garlic, grated ginger, honey, and red pepper flakes until fully combined. This marinade is your foundation - the soy brings umami, the citrus cuts through the richness of the tuna, and the honey is going to help build that beautiful caramelized crust once the steaks hit the fire.

Pat your tuna steaks completely dry with paper towels before adding them to the marinade. Moisture is the enemy of a good sear - if your tuna is wet when it hits the grate, it will steam instead of sear. Submerge the steaks in the marinade, cover, and refrigerate for 20 to 30 minutes maximum. Do not over-marinate tuna - the citrus acids will start to break down the protein if you leave it too long, and you will lose that firm, meaty texture we are going for.

While the tuna marinates, fire up the grill. For charcoal, you want a full chimney of lit coals spread in an even layer for direct high heat. Your target grate temperature is 450 to 500 degrees Fahrenheit. For gas grillers, crank all burners to high and close the lid for 10 to 15 minutes to fully preheat. You want those grates screaming hot - this is what creates the sear and those iconic grill marks.

Once your grill is up to temp, take a folded paper towel soaked in olive oil and use your long tongs to wipe the grates down thoroughly. This step is non-negotiable. A clean, oiled grate is the difference between tuna that releases cleanly with a perfect crust and tuna that tears apart and sticks. Do this right before you add the steaks - every single time.

Pull the tuna steaks out of the marinade and let any excess drip off. Season both sides with kosher salt and cracked black pepper right before they go on. Do not add salt during marinating - it draws out moisture. Lay the steaks on the grill at a 45-degree angle to the grates. You will hear that satisfying sizzle immediately - that is exactly what you want. Close the lid and let them sear undisturbed for 2 to 2.5 minutes.

After 2 to 2.5 minutes, open the lid and rotate each steak 90 degrees on the same side - this creates those classic crosshatch grill marks and ensures even contact with the hot grates. Close the lid again and sear for another 1.5 to 2 minutes. You should see the edges of the tuna beginning to turn opaque and the bottom developing a deep mahogany crust.

Flip the tuna steaks carefully using your long tongs - do not use a spatula that could break the crust you just built. Repeat the same process on the second side: 2 to 2.5 minutes sear, then a 90-degree rotate for crosshatch marks, then another 1.5 to 2 minutes. For a perfect medium-rare finish, you are targeting an internal temp of 125 degrees Fahrenheit at the center of the thickest steak. For medium, pull at 130 to 135 degrees Fahrenheit.

Pull the steaks off the grill and immediately move them to your cutting board. This is where you rest the meat - even though tuna cook times are short, a 3 to 5 minute rest allows the juices to redistribute through the steak. Tent loosely with foil if desired, but do not seal tightly or you will trap steam and soften that crust you worked hard to build.

To finish and plate, sprinkle the rested tuna steaks generously with black and white sesame seeds and fresh sliced scallions. If you want to add a final punch of flavor, drizzle a small amount of toasted sesame oil over the top right before serving. Slice against the grain at a slight diagonal to show off that gorgeous pink-to-seared gradient interior. Serve immediately while the crust is still crackling.