Pat shrimp dry with paper towels. If using larger shrimp, butterfly or make a shallow cut along the belly and remove vein. Lightly season with 1/4 tsp salt.

Make batter

In a bowl, combine 1/2 cup all-purpose flour and 2 tsp cornstarch. In a separate small bowl, beat 1 egg and add 1/2 cup ice-cold sparkling water. Pour wet mixture into dry ingredients and stir lightly with chopsticks or a fork; batter should be lumpy and just combined (do not overmix). Keep batter cold.

Heat oil

Pour 3 cups vegetable oil into a deep, heavy pot or deep fryer. Heat to 350–360°F (175–180°C). If you don't have a thermometer, test by dropping a small amount of batter—should sizzle and rise immediately.

Fry shrimp to tempura

Dust shrimp lightly with a teaspoon of flour if desired. Dip each shrimp into batter, shake off slight excess, and carefully lower into hot oil. Fry in batches for 2–3 minutes until light golden and crisp. Remove with a slotted spoon and drain on a wire rack or paper towels. Keep warm and crisp while you assemble rolls.

Roll Filling

Prepare crab mix

In a small bowl, flake 4 oz crab meat and combine with 1 tablespoon mayonnaise, 1/2 teaspoon soy sauce and 1/2 teaspoon sriracha (optional). Mix until evenly combined and taste; adjust seasoning if necessary.

Prepare avocado and cream cheese

Slice the avocado in half, remove the pit, scoop out flesh and slice into long thin strips (about 1/4 inch thick). Cut 4 oz cream cheese into 8 thin batons (approximately 1/4 inch x 1/4 inch x 2–3 inch).

Assembly & Finish

Prepare sushi rice and nori

Have 3 cups cooked, seasoned sushi rice at room temperature. Place a bamboo mat on a flat surface and cover it with plastic wrap to prevent sticking. Place 1 nori sheet (shiny side down) on the mat.

Spread rice

Wet your fingers with a little water to prevent sticking. Spread about 3/4 cup of sushi rice evenly over the nori, leaving a 1-inch (2.5 cm) strip at the far edge clear for sealing. Lightly press rice to an even layer about 1/4 inch thick. Sprinkle a few toasted sesame seeds over the rice if desired.

Flip nori & add fillings

Carefully flip the nori so rice faces down on the plastic wrap/mat. On the nori side (now facing up), place two tempura shrimp lengthwise about 1 inch from the near edge. Alongside the shrimp, add 2 cream cheese batons, a few avocado slices, and a generous spoonful (about 1 tablespoon) of the crab mix spread evenly in a line.

Roll

Using the bamboo mat, lift the near edge and roll firmly but gently away from you, tucking the fillings in as you go. Roll until the seam seals; use a little water on the bare nori strip to help seal if necessary. Apply gentle pressure with the mat to shape the roll into a tight cylinder. Repeat to make 4 rolls (use remaining nori and fillings).

Slice

Using a very sharp knife dipped in water (wipe clean between cuts), slice each roll into 6–8 equal pieces. For neat slices, press down once, then slice in a single clean motion. Wipe the knife between cuts.

Plate and serve

Arrange pieces on a platter. Garnish with additional crab mix on top of each piece or a thin slice of avocado if desired. Serve immediately with soy sauce, pickled ginger, and wasabi.