Rinse the sushi rice for a minute or two until the water runs clear. If you have time, soak it in water for 15 minutes prior to rinsing.
Add 3 cups of water to a pot over high heat and bring to a boil. Add the salt and rice and once boiling, lower the heat and cover to simmer for 20 minutes. 3. After, turn off the heat but leave covered for 10 more minutes. Then fluff it up.
In a small bowl, add the rice vinegar, granulated sugar, and sesame oil. Microwave for 30 seconds or quickly warm it up in a pot just so the sugar dissolves.
Pour this over the rice and mix so that each grain of rice is coated evenly. It should be very sticky! Set aside.
MAKE THE SPICY TUNA
To a bowl, add the finely diced tuna along with mayonnaise, sriracha, soy sauce, sesame oil, lime juice, and sliced green onions.
Mix together.
ASSEMBLY
Using hands dipped in water, shape about ¼ cup of rice into a small triangle on a piece of saran wrap.
Add about 2 tablespoons of spicy tuna filling to the center. Cover with more rice on top in the shape of a triangle.
Wrap with Saran Wrap tightly and shape tightly. Then unwrap it. Repeat with the rest of the rice and tuna. You can also add thinly sliced avocado inside. 4. Wrap a piece of nori along the bottom.
MAKE THE SUSHI RICE
OPTIONAL STEP: To make this yaki (which just means grilled in Japanese), add a splash of oil to a pan. Do not add a lot of oil, just enough to cover the surface of the pan. Add the onigiri and fry on each side for 3 minutes until crispy and golden. Then add a drizzle of Japanese barbecue sauce on one side and flip over so the barbecue sauce can caramelize. Repeat on the other side. Take off the heat and wrap a piece of nori along the bottom.
