Rinse 2 cups of sushi rice under cold water until the water runs clear. Cook the rice with 2.5 cups of water for about 15-20 minutes, then set aside to cool slightly.

In a medium bowl, combine 1/4 cup of rice vinegar, 2 tablespoons of sugar, and 1 teaspoon of salt. Stir until the sugar and salt dissolve.

Fluff the cooled sushi rice and mix it with the vinegar mixture. Spread evenly in a greased 9x9-inch baking dish, pressing down gently.

In a large bowl, dice 8 ounces of fresh salmon fillet. Mix with 1/4 cup of mayonnaise, 2 tablespoons of sriracha sauce, 1 teaspoon of sesame oil, and 2 chopped green onions until well combined.

Spread the salmon mixture over the rice base evenly, pressing down gently.

Preheat oven to 375°F (190°C). Bake for 25-30 minutes until salmon is cooked through and top is golden brown.

Let cool briefly, garnish with additional green onions, nori strips, and tobiko before serving warm.