Preheat your oven to 375°F (190°C).
Cook the sushi rice according to package instructions.
In a mixing bowl, combine rice vinegar, sugar, and salt. Stir until dissolved. Fluff the cooked rice and fold in the vinegar mixture.
Spread the seasoned rice evenly at the bottom of your baking dish and let it cool slightly.
Mix together diced salmon, mayonnaise, Sriracha sauce, sesame oil, and chopped green onions until well combined.
Spread the salmon mixture evenly over the cooled rice in your baking dish.
Bake in the preheated oven for about 25-30 minutes or until the salmon is cooked through and the top is slightly golden.
Once baked, remove from the oven and let it cool for a few minutes. Garnish with additional green onions, nori strips, and tobiko if desired.
Serve warm by scooping out portions with a spoon.