Cook the Rice: Prepare sushi rice according to package directions. For best results, rinse thoroughly before cooking.
Season the Rice: While the rice is still warm, mix in the rice vinegar, sugar, and salt mixture. Fold gently with a wooden spoon or rice paddle to keep it fluffy.
Make the Spicy Mayo: In a small bowl, whisk together mayonnaise, sriracha, soy sauce, and sesame oil. Chill in the fridge to let the flavors blend.
Assemble the Bowl: Start with a bed of sushi rice in each bowl. Top with crab, avocado, cucumber, and strips of nori.
Drizzle & Serve: Finish with a generous drizzle of spicy mayo. Add sesame seeds or green onions if desired, and enjoy!