Rinse sushi rice under cold water until water runs clear. Cook according to package instructions with a dash of salt.

Slice cucumber and avocado into thin strips, about a quarter inch thick.

Prepare a bamboo sushi mat covered with plastic wrap. Place a sheet of nori on the mat, shiny side down.

Wet your fingers to prevent sticking. Scoop and spread about 1 cup of sushi rice over two-thirds of the nori sheet.

Add a line of cooked shrimp or crab, cucumber, and avocado along the center of the rice-covered nori. Drizzle with sriracha sauce.

Gently lift the edge of the mat and roll away from you, applying pressure, until you reach the exposed edge. Wet it to seal.

Slice the rolled sushi into eight equal pieces using a sharp knife dipped in water. Arrange on a platter and serve.