Rinse the sushi rice until the water runs clear. If you have time, soak it in water for 15 minutes before rinsing.

In a pot over high heat, bring 3 cups of water to a boil. Add salt and rice, then lower the heat and cover to simmer for 20 minutes. Turn off the heat but leave covered for an additional 10 minutes, then fluff the rice.

In a small bowl, combine rice vinegar, granulated sugar, and sesame oil. Microwave for 30 seconds or warm it in a pot until the sugar dissolves. Pour over the rice and mix until evenly coated. Set aside.

In a bowl, mix finely diced tuna with mayonnaise, sriracha, soy sauce, sesame oil, lime juice, and sliced green onions.

Shape about 1/4 cup of rice into a small triangle using hands dipped in water, on a piece of plastic wrap.

Add about 2 tablespoons of spicy tuna filling to the center, then cover with more rice in a triangle shape.

Wrap tightly with plastic wrap, then unwrap. Repeat with remaining rice and tuna. You can add sliced avocado inside if desired. Wrap a piece of nori along the bottom.

Optional Step: To grill (yaki) the onigiri, add a splash of oil to a pan, fry each side for 3 minutes until crispy and golden. Drizzle Japanese barbecue sauce and caramelize. Repeat on the other side.

Enjoy with spicy mayo or chili oil for dipping!