Cut the tuna into cubes.
Slice the onion and cucumber thinly.
Halve the avocado and dice it.
Place the sliced ingredients, imitation crab, corn, etc. on top of the rice.
Make a sauce by mixing soy sauce, sesame oil, wasabi, and minced garlic.
Drizzle the sauce evenly over the ingredients.
Finish by sprinkling seaweed flakes and sesame seeds.