Prepare the Rice: Begin by rinsing the sushi rice under cold water until the water runs clear. This removes excess starch and helps achieve a perfect texture.
Cook the Rice: In a rice cooker or pot, combine the rinsed rice and water. Add salt. Cook according to the rice cooker instructions or bring to a boil, cover, reduce heat, and simmer for about 18 minutes, or until the water is absorbed.
Season the Rice: In a small bowl, mix rice vinegar and sugar until dissolved. Once the rice is cooked, transfer it to a large bowl and gently fold in the vinegar mixture using a wooden paddle or spatula. Allow it to cool slightly.
Prepare the Chicken Filling: In a bowl, mix the shredded chicken with soy sauce, sesame oil, and chopped green onion. Ensure the chicken is well-coated with the sauce.
Form the Onigiri: With slightly wet hands (to prevent sticking), take about 1/3 cup of rice and flatten it into a small disc in your palm. Place a spoonful of the chicken mixture in the center. Carefully fold the rice around the filling, shaping it into a triangle or oval form. Repeat until all the rice and filling are used.
Wrap with Nori: Take a strip of nori and wrap it around the base of each onigiri. This adds flavor and makes it easier to hold. If desired, sprinkle with sesame seeds for extra crunch.