Rinse the sushi rice under cold water until the water runs clear. This helps remove excess starch for better texture.
Combine the rinsed rice and water in a saucepan. Bring to a boil, then reduce heat to low, cover, and simmer for about 15 minutes or until the rice is tender and water is absorbed.
While the rice is cooking, in a small bowl, mix the rice vinegar, sugar, and salt until dissolved. Once the rice is done, transfer it to a large bowl and gently fold in the vinegar mixture. Allow it to cool to room temperature.
Place a bamboo sushi mat on a flat surface and lay a sheet of nori, shiny side down.
Wet your hands to prevent sticking, and take about ½ cup of sushi rice, evenly spreading it over the nori, leaving about 1 inch of space at the top edge.
Lay cucumber and avocado strips horizontally across the center of the rice-covered nori.
Carefully roll the sushi away from you, using the bamboo mat to keep everything tight. Press gently but firmly as you roll.
Once rolled, use a sharp, wet knife to slice the sushi into bite-sized pieces—about 6 to 8 pieces per roll.
Repeat with the remaining ingredients to make more rolls.
Serve the sushi rolls with soy sauce, pickled ginger, and a sprinkle of sesame seeds if desired.
Notes
Use a sharp knife to slice the sushi for clean cuts.