Rinse the sushi rice under cold water until the water runs clear. Cook rice with 1.25 cups of water in a rice cooker or pot. Once cooked, fold in rice vinegar, sugar, and salt, and let cool.

Heat oil in a deep fryer or pot to 350°F (175°C).

Mix flour, cornstarch, and baking powder in a bowl. Gradually add ice-cold water to make tempura batter.

Coat chicken strips in batter and fry until golden brown, about 3–4 minutes. Drain on paper towels.

Place plastic wrap on a bamboo sushi mat, lay nori shiny-side down, and spread rice evenly over it, leaving a border.

Add tempura chicken, avocado slices, and cucumber near the bottom. Roll tightly using the mat.

Slice the roll into 6–8 pieces with a sharp knife. Serve with spicy mayo made from mayo and sriracha.