Place the rice in a fine-meshed sieve and rinse well under cold water until the water runs clear. Drain well.

Combine the rice and cold water, and cook in a rice cooker according to the manufacturer?s directions. If using a saucepan, combine the rice and water, bring to a boil, reduce heat to low, cover, and cook for 16 to 18 minutes until the water is absorbed. Remove from heat, fluff the rice, cover with a kitchen towel and lid, and let stand for 10 minutes.

In a medium bowl, combine the tuna, mayonnaise, hot sauce, and rice vinegar until evenly mixed. Stir in the scallions.

Set aside a bowl of room temperature water and a small bowl of kosher salt. Once the sushi rice is cool enough to handle, moisten hands with water and sprinkle with salt.

Grab roughly ? cup of sushi rice and press it into an oblong shape in one palm. Add a tablespoon of the tuna filling to the center of the rice and envelop the filling with the rice.

Shape the rice ball into a triangular shape using your palms and fingers without compressing too hard. Sprinkle the outside with black sesame seeds. Wrap each onigiri in a nori sheet and place additional tuna filling on top. Serve immediately.