Yellowtail
Rinse the sushi rice under cold water until the water runs clear. Cook the rice according to your rice cooker's instructions or on the stovetop. Once cooked, transfer the rice to a large bowl.
In a small saucepan, combine rice vinegar, sugar, and salt. Heat until the sugar dissolves. Pour this mixture over the warm rice and gently fold it in with a spatula. Allow the rice to cool to room temperature.
Wet your hands with water to prevent sticking. Take a small amount of sushi rice (about 2 tablespoons) and shape it into an oval mound. Repeat until all rice is used.
Slice the fresh Hamachi into thin pieces. Place a slice of Hamachi on top of each rice mound. If desired, add a small dab of wasabi between the rice and the fish.
Arrange the Hamachi nigiri on a plate. Optionally, cut the nori sheet into thin strips and use it to garnish. Serve with soy sauce on the side for dipping.