Cook the sushi rice. Let it cool.
Mix vinegar, sugar, salt into rice. Stir well.
Lay plastic wrap on bamboo mat. Place nori.
Spread rice on nori. Press it gently.
Flip the nori so rice faces down.
Add crab mix, avocado, and cucumber inside.
Roll tightly using the bamboo mat.
Roll again to secure the shape.
Toast tempura flakes in a skillet briefly.
Spread spicy mayo over the roll top.
Press toasted flakes gently on top.
Slice roll using a wet sharp knife.
Sprinkle sesame seeds if desired. Serve with soy sauce.