Rinse the sushi rice under cold water until the water runs clear.

Combine the rinsed rice and water in your rice cooker or pot. Cook according to the appliance instructions or bring to a boil, then simmer for 15 minutes.

Once cooked, let the rice sit for about 10 minutes to firm up.

In a mixing bowl, combine the drained tuna, mayonnaise, sriracha, soy sauce, and sesame oil. Mix until well blended.

Once the rice has cooled a bit, season with salt to taste.

Wet your hands and take a handful of rice, flatten it slightly, and place a spoonful of the tuna mixture in the center. Mold the rice around the filling to form a triangle.

If using nori, cut it into strips and wrap around the base of the onigiri.

Serve immediately or pack for later.