Rinse the sushi rice until the water runs clear. In a pot, combine rice and water, bring to boil, reduce heat, cover, and simmer for 18-20 minutes until tender. Let rest covered for 10 minutes.

In a small bowl, whisk together rice vinegar, sugar, and salt until dissolved. Set aside.

Fluff the rice with a fork, gently fold in vinegar mixture, and spread the seasoned rice into a greased baking dish.

In a bowl, combine diced salmon, mayonnaise, sriracha, and sesame oil. Stir until coated, mix in green onions.

Spoon the salmon topping over the rice layer in the baking dish, spreading it out evenly.

Preheat the oven to 375°F (190°C). Bake for 25-30 minutes until bubbly and golden brown.

Remove from oven and let cool slightly. Garnish with green onions, nori, and optional tobiko. Serve warm.