Rinse the sushi rice under cold water until the water runs clear. Combine the rinsed rice and water in a rice cooker and cook according to the manufacturer's instructions. Once cooked, let it sit for 10 minutes before fluffing with a fork.

In a small saucepan, combine rice vinegar, sugar, and salt. Heat over low heat until the sugar dissolves. Pour the mixture over the cooked rice and gently fold to combine. Allow the rice to cool to room temperature.

Preheat your broiler. Place the salmon fillet on a baking sheet lined with foil. In a small bowl, mix soy sauce and sesame oil, then brush the mixture over the salmon.

Broil the salmon for about 6-8 minutes, or until the top is caramelized and the fish is cooked through. Remove from the oven and let it rest for a few minutes before slicing.

To assemble, take a scoop of sushi rice and form it into a small ball or mound. Top with a slice of avocado and a piece of broiled salmon. Sprinkle with chopped green onions and sesame seeds. If using, add a strip of nori for garnish.

Serve immediately and enjoy!