In a small bowl, whisk together the soy sauce, sesame oil, grated ginger, minced garlic, salt, and pepper. This will be your marinade.
Place the Ahi tuna steaks in a shallow dish and pour the marinade over them, ensuring both sides are coated. Let it marinate for at least 15 minutes.
While the tuna is marinating, spread the sesame seeds in a shallow plate.
Remove the tuna from the marinade and gently press both sides into the sesame seeds, ensuring they are evenly coated.
Heat the vegetable oil in a skillet over medium-high heat. Once hot, carefully add the sesame-crusted tuna steaks.
Sear the tuna for about 1-2 minutes on each side for a rare to medium-rare finish, without overcooking. The exterior should be golden brown while the interior remains pink.
Remove the tuna from the skillet and let it rest for a minute before slicing.
Slice the tuna steaks against the grain into thin strips.
Arrange the sliced tuna on a plate, garnishing with fresh cilantro and serving lime wedges on the side.
Notes
For best results, do not overcook the tuna to maintain its pink interior.