Place the uncooked short grain rice in a medium sauce pot. Cover with cool water, swish the rice around, then carefully pour off the cloudy water. Repeat this rinsing process 3-4 times. Finally, add 2 cups fresh water, place a lid on the pot, and place the pot over high heat. Allow the pot to come to a full boil, then turn the heat down to low and let simmer for 15 minutes. After 15 minutes, turn the heat off and let the rice rest, undisturbed and with the lid in place, for 10 additional minutes.
While the rice is cooking, prepare the toppings. Shred the crab stick, shred or julienne the carrot, slice the avocado, slice the cucumber, and break the nori into smaller pieces. Stir together the mayonnaise and sriracha in a small bowl.
For the sushi rice dressing, combine the rice vinegar, sugar, and salt in a small bowl. Microwave for 15-20 seconds to warm the mixture, then stir until the sugar is fully dissolved.
Once the rice is finished cooking, transfer it to a large bowl. Sprinkle about 1/4 of the vinegar dressing over the rice, then gently fold or stir the rice to combine. Repeat the process until all of the vinegar dressing has been incorporated into the rice and the rice has taken on a glossy appearance.
To build your sushi bowls, place about 1 cup of the seasoned sushi rice in a bowl, then top with crab stick, carrot, cucumber, avocado, a few pieces of nori, a pinch of sesame seeds, and a drizzle of the sriracha mayo.