Rinse the sushi rice under cold water until the water runs clear. Combine the rice and water in a saucepan and bring to a boil.

Reduce heat to low, cover, and simmer for 15 minutes. Remove from heat and let it sit covered for 10 minutes.

In a small bowl, mix rice vinegar, sugar, and salt until dissolved. Stir into the cooked rice and let cool.

Preheat the oven to 400°F (200°C).

Place the salmon fillet on a baking sheet, drizzle with soy sauce and sesame oil, and bake for 15-20 minutes until cooked through.

Once cooked, flake the salmon into a bowl and mix in chopped green onions and mayonnaise.

Preheat the muffin tin by lightly greasing it. Press a small amount of sushi rice into each muffin cup, forming a cup shape.

Fill each rice cup with the salmon mixture, then top with avocado slices and pickled ginger.

Serve immediately with wasabi on the side if desired.