Cut salmon and tuna into bite-sized pieces.
Dice cucumber, avocado, and onion finely.
Put rice into a bowl.
Place salmon, tuna, cucumber, avocado, and onion on top of the rice.
Mix soy sauce, sesame oil, and lemon juice to make a sauce.
Drizzle the sauce over the ingredients.
Finish by topping with seaweed and sesame seeds.