Rinse 2 cups of short-grain white rice under cold water until clear, cook according to instructions, and mix with vinegar, sugar, and salt after cooking.

Slice avocado and julienne cucumber while the rice cools, cut the imitation crab into pieces.

Place a sheet of nori on a bamboo mat, wet fingers, and spread about 1 cup of sushi rice evenly on the nori.

Layer avocado, cucumber, and imitation crab on the rice, and roll tightly using the bamboo mat.

Seal the roll with wet edges of nori and gently press to shape.

Sprinkle tempura flakes on top of the rolled sushi and press lightly to adhere.

Slice the roll into eight equal pieces using a sharp, wet knife.