Rinse sushi rice under cold water until water runs clear, then combine in a rice cooker with water and cook according to instructions.

Transfer cooked rice to a bowl, mix together rice vinegar, sugar, and salt until dissolved, then fold into rice.

Slice cucumber thinly and dice avocado right before serving.

Scoop seasoned sushi rice into bowls and layer with cucumber, avocado, and crab meat.

Combine soy sauce with sriracha if desired, drizzle over bowls, and serve immediately.

Encourage guests to mix their bowls, and offer sesame seeds or nori strips on the side.