Drain the tuna and add to a medium sized bowl. Flake apart with a fork.
Add kewpie mayo, sriracha, and sesame oil to the tuna and mix until well combined.
You can adjust the mayo and sriracha ratio to meet your preferences.
Start by laying a piece of nori on saran wrap.
Add a scoop of the sushi rice to the nori, a layer of sliced cucumber, and then add a small amount of the spicy tuna mixture and avocado to the center.
Use the saran wrap to wrap up the nori until it forms a ball.
Remove the saran wrap, slice the onigiri ball in half, and enjoy!
