Rinse 1 cup of sushi rice under cold water until clear. Cook according to package instructions, then mix in 2 tbsp rice vinegar, 1 tbsp sugar, and a pinch of salt.

In a medium bowl, combine 1/2 cup flour, 2 tbsp cornstarch, and 1/2 tsp baking powder. Gradually add 1 cup soda water, mixing until just combined.

Heat vegetable oil in a deep frying pan to 350°F (175°C).

Dip shrimp in batter and fry in batches for 2-3 minutes until golden brown. Drain on paper towels.

Spread sushi rice on nori, add tempura shrimp, avocado, and cucumber. Roll tightly and seal the edge with water.

Slice the roll into 6-8 pieces and serve with sesame seeds and soy sauce.