Rinse sushi rice under cold water until nearly clear, then cook with water according to package directions.
Season hot cooked rice by folding in the rice vinegar, sugar, and salt mixture until glossy and just warm.
Mix mayonnaise and sriracha together in a small bowl to make the spicy mayo sauce.
Divide seasoned rice between bowls and top with crab, avocado, and cucumber arranged in sections.
Finish with nori strips, toasted sesame seeds, a drizzle of sriracha mayo, and soy sauce and pickled ginger on the side.