Peel and grate the ginger. Place the tuna steaks in a medium bowl and start by rubbing the grated ginger onto both sides.
In a small bowl combine the olive oil, lemon juice and coconut aminos and pour evenly onto both sides of the steaks. Season both sides with garlic powder, sea salt and pepper. Let it marinade for 15 minutes.
Heat a large pan over medium high heat until hot. Make sure the steaks are covered with the marinade before you place them in the pan. Sear the steaks for 1-2 minutes on each side for rare. Depending on how you like your tuna steak cooked you will sear it longer. If the pan is getting too hot, lower the temperature to medium.
Once the tuna is done, simply place it on a plate and serve it with your favorite side or cut it into slices.
Optionally sprinkle with sesame seeds.
Enjoy!