Cook the sushi rice. Once cooked, mix in the sushi vinegar. Leave it to cool to room temperature.
Mix sriracha sauce and mayonnaise together in a bowl. After shredding the crab meat, add the sriracha mayo and mix it well. Toast the nori sheet.
Place a sushi bamboo mat on a clean flat surface, place a sheet of cling wrap on top. Cut a piece of seaweed into two halves, and spread a thin layer of rice on a piece of seaweed. Gently press the rice with a spoon to flatten it, then sprinkle gomashio on top of it.
Now, flip the rice and nori sheet, so that your seaweed is facing up. You can then add the spicy Kani salad in Step 2 to the middle of the nori sheet. Add the avocado, cucumber, and mango on top of it, with some mayonnaise.
Roll the bamboo mat starting at the edge with both hands pressing it down firmly, continue until you reach the end. Leave in the fridge for at least 60 minutes or in the freezer for only 15 minutes. You can now cut your kani maki into pieces and remove the cling wrap for serving.
If you like, you can place your masago on a plate, then roll each sushi slice onto the masago. Now you can serve your spicy crab roll!
If the local supermarket does not sell sushi vinegar, a mixture of rice vinegar, sugar, and salt will suffice.