Cut the salmon and avocado into bite-sized pieces.
Slice the onion thinly and soak in cold water to remove the sharp flavor.
Place rice in a bowl.
Top the rice with salmon, avocado, onion, cucumber, and seaweed flakes.
Mix soy sauce, sesame oil, and lemon juice to make the dressing.
Drizzle the dressing evenly over the ingredients.
Finish with sesame seeds and wasabi to taste.