Rinse 2 cups of sushi rice under cold water until water runs clear, then cook rice according to package instructions.

Mix in 3 tablespoons rice vinegar, 1 tablespoon sugar, and ½ teaspoon salt to the warm rice and cool to room temperature.

In a medium bowl, combine 1 cup shredded crab meat, 3 tablespoons mayonnaise, and 1 tablespoon sriracha; stir to coat.

Lay a sheet of nori on a bamboo mat with the shiny side down, spread sushi rice leaving 1 inch at one edge.

Flip the nori so the rice is at the bottom; layer half the crab mix, avocado slices, and cucumber evenly on the rice.

Starting from the edge closest to you, roll the sushi using the bamboo mat, applying firm pressure but not too hard.

Optional: spread remaining crab mixture on top, wrap in cling film, and press gently.

Slice the roll into 8 equal pieces using a sharp, wet knife, and serve with soy sauce, pickled ginger, and wasabi.