Rinse the sushi rice thoroughly under cold water until the water runs clear. In a medium pot, combine the rinsed rice with water and bring to a boil. Once boiling, reduce the heat to low, cover, and simmer for about 15 minutes or until the rice is tender. After that, let it rest covered for another 10 minutes.

In a small bowl, whisk together rice vinegar, sugar, and salt until fully dissolved. Once the rice has rested, gently fold this mixture into the cooked sushi rice using a spatula.

Spread the seasoned sushi rice evenly across the bottom of a 9x13 inch baking dish, pressing it down gently.

In a mixing bowl, combine the diced salmon, mayonnaise, sriracha, sesame oil, and chopped green onions. Mix thoroughly until all the ingredients are well incorporated.

Carefully spread the salmon mixture evenly over the rice layer in the baking dish.

Preheat your oven to 375°F (190°C) and bake for 25-30 minutes, or until the top is golden and bubbly, and the salmon is cooked through.

Once baked, remove the dish from the oven and allow it to cool slightly. Garnish with additional green onions, nori strips, and tobiko if desired. Serve warm.