Prepare the Sushi Rice: Rinse the sushi rice under cold water until the water runs clear. Combine rice and water in a pot, bring to a boil, then cover, reduce heat to low, and simmer for 15 minutes. Remove from heat and let stand, covered, for 10 minutes.

Make the Sushi Seasoning: While the rice rests, gently warm the rice vinegar, sugar, and salt in a small saucepan until the sugar and salt dissolve completely. Do not boil.

Season the Rice: Transfer the cooked rice to a large, non-metallic bowl. Drizzle the seasoning mixture evenly over the rice. Using a cutting motion with a spatula, gently fold the seasoning into the rice while fanning it slightly to cool it down quickly. Set aside to cool to room temperature.

Prepare Toppings and Sauce: Dice the avocado and cucumber. Shred or chop the imitation crab. For the spicy mayo, whisk together the mayonnaise, sriracha, and lime juice in a small bowl until smooth. Set aside.

Assemble the Bowls: Evenly divide the seasoned sushi rice among four serving bowls. Arrange the shredded crab, diced avocado, and diced cucumber attractively over the top of the rice in sections.

Garnish and Serve: Drizzle generously with the prepared spicy mayo. Sprinkle with toasted sesame seeds and strips of nori seaweed. Serve immediately.