01 - Place sushi rice in a fine-mesh strainer and rinse under cold running water, gently swirling with your hand, until the water runs completely clear. Drain thoroughly.
02 - Transfer the rinsed rice and 2 cups of water to a medium saucepan. Bring to a rolling boil over medium-high heat, then cover with a tight-fitting lid. Reduce heat to low and simmer for 15 minutes. Remove from heat and let rest, covered, for 10 minutes without lifting the lid.
03 - While the rice rests, whisk together rice vinegar, sugar, and salt in a small bowl until fully dissolved. Transfer the warm rice to a large mixing bowl, pour the vinegar mixture over it, and gently fold with a rice paddle using a slicing motion. Fan the rice briefly to cool and achieve a glossy finish.
04 - Shred the imitation crab sticks into fine pieces. Dice the avocado, julienne the cucumber into thin matchsticks, slice the nori sheets into thin strips, and chop the pickled ginger. Thinly slice the green onion and set all toppings aside.
05 - In a small bowl, combine the mayonnaise with sriracha to taste. Stir until smooth and well blended.
06 - Divide the seasoned rice evenly among four serving bowls. Arrange the shredded crab, diced avocado, julienned cucumber, nori strips, and chopped pickled ginger in sections over each bed of rice.
07 - Drizzle each bowl with spicy mayo and soy sauce. Finish with a generous sprinkle of toasted sesame seeds and sliced green onions. Serve immediately with additional soy sauce on the side.