01 - Rinse the sushi rice under cold water until the water runs clear. Combine rice and water in a saucepan, bring to a boil, reduce heat to low, cover, and cook for 15 minutes. Remove from heat and let sit, covered, for 10 minutes.
02 - In a small bowl, mix rice vinegar, sugar, and salt until fully dissolved. Gently fold the mixture into the cooked rice using a cutting motion, being careful not to mash the grains. Allow the rice to cool to room temperature.
03 - In a small bowl, whisk together the mayonnaise and sriracha until smooth and well combined. Set aside for drizzling.
04 - Divide the seasoned sushi rice among four serving bowls. Arrange the shredded imitation crab, sliced avocado, julienned cucumber, carrot if using, and nori strips attractively over the rice in each bowl.
05 - Drizzle the spicy mayo over each bowl, sprinkle generously with toasted sesame seeds, and serve immediately with pickled ginger and soy sauce on the side.