Rinse the sushi rice under cold water until the water runs clear. Cook the rice according to your rice cooker instructions or on the stove with 2 cups of water. Once cooked, let it cool slightly.

Season the Rice

In a small bowl, combine rice vinegar, sugar, and salt. Heat gently until the sugar dissolves. Pour this mixture over the rice and gently fold it in. Allow the rice to cool to room temperature.

Prepare the Fillings

Thinly slice the fresh fish, cucumber, and avocado. Set aside.

Assemble the Sushi Rolls

Place a nori sheet on a bamboo sushi mat. Wet your hands and spread a thin layer of sushi rice over the nori, leaving about an inch at the top. Layer the fish, cucumber, and avocado in the center. Roll the mat away from you, pressing gently but firmly to shape the sushi. Seal the edge with a little water.

Slice and Serve

Use a sharp knife to slice the sushi roll into bite-sized pieces. Serve with soy sauce, wasabi, and pickled ginger on the side.