Rinse the sushi rice under cold water until the water runs clear. Cook the rice according to the package instructions. Once cooked, transfer to a bowl.

Season the Rice

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

Prepare Fillings

While the rice cools, slice the fresh fish, cucumber, and avocado into thin strips.

Assemble the Sushi

Place a bamboo mat on a flat surface. Lay a nori sheet on the mat, shiny side down. Wet your hands to prevent sticking and take a handful of sushi rice, spreading it evenly over the nori, leaving about an inch at the top. Arrange your fish, cucumber, and avocado in a line across the center of the rice.

Roll the Sushi

Using the bamboo mat, carefully roll the sushi away from you, applying gentle pressure to form a tight roll. Seal the edge with a little water.

Slice and Serve

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