Dice fresh salmon and tuna into cubes.
Cut avocado, cucumber, and onion into bite-sized pieces.
Put rice in a bowl.
Place the prepared salmon, tuna, and vegetables on top of the rice.
Mix soy sauce, sesame oil, lemon juice, and a bit of sugar to make the sauce.
Drizzle the sauce evenly over the top.
Sprinkle with sesame seeds and seaweed flakes to finish.