01 - Rinse sushi rice under cold running water until the runoff turns completely clear. Combine the rinsed rice with 2 cups of water in a rice cooker or saucepan and cook according to package directions until tender and all liquid is absorbed.
02 - While the rice is still hot, whisk together rice vinegar, sugar, and salt in a small bowl. Microwave for 20 seconds to help the sugar and salt dissolve fully, then pour the seasoned vinegar over the hot rice. Fold gently with a spatula, taking care not to mash the grains, and let the rice cool to room temperature.
03 - Shred or chop the imitation crab into bite-sized pieces. Dice the avocado and seeded cucumber into uniform cubes. Slice the green onions thinly and cut the nori sheets into thin strips. Set all toppings aside.
04 - Combine the Japanese mayonnaise with sriracha in a small bowl and stir until smooth. Adjust the amount of sriracha to reach your preferred heat level.
05 - Divide the seasoned sushi rice evenly among 4 bowls. Arrange the crab, avocado, cucumber, nori strips, and pickled ginger on top of each portion. Drizzle with spicy mayo and finish with a generous sprinkle of toasted sesame seeds and sliced green onions.
06 - Serve immediately with soy sauce and wasabi on the side for dipping and seasoning to taste.