Rinse 2 cups short-grain sushi rice until water runs clear, removing excess starch.

Cook using a 1:1.2 rice-to-water ratio, then fold in seasoning mixture of rice vinegar, sugar, and salt while warm.

Cool to room temperature, covering with a damp towel to prevent drying.

Whisk together flour, baking powder, and salt in a large bowl.

Separately combine ice-cold water with egg yolk—cold temperature ensures crispy texture.

Gently fold wet into dry ingredients using chopsticks, mixing just until barely combined. Keep batter lumpy; overmixing creates heavy coating instead of delicate crispiness.

Heat oil to exactly 340°F using a candy thermometer.

Cut chicken breast into finger-sized strips and season lightly.

Working in small batches, dip each piece in batter just before frying for 3-4 minutes until golden brown and internal temperature reaches 165°F. Transfer to wire rack immediately.

Place nori sheet shiny-side down on bamboo mat.

With wet hands, spread thin rice layer leaving 1-inch top border. Arrange tempura chicken horizontally across center, add cucumber and avocado.

Roll tightly from bottom using bamboo mat as guide, sealing edge with water drops.

Using sharp, wet knife, slice your chicken tempura in smooth motions to prevent crushing. Clean blade between cuts, divide into 8 equal pieces, and arrange cut-side up with traditional accompaniments.