Cut the tuna into bite-sized pieces.
Mix soy sauce, cooking wine, sesame oil, sugar, and lemon juice to make the sauce.
Combine the cut tuna with the sauce and mix well.
Place rice in a bowl and add lettuce on top.
Add the tuna, avocado, cucumber, onion, and other toppings over the rice.
Sprinkle seaweed flakes and sesame seeds to finish.