Let the rice cool till you can comfortably handle it. To do this, transfer the rice to a plate or baking sheet lined with parchment paper, a wooden chopping board, or a sushi oke/hangiri if you have one. This should just take a few minutes. If you leave it too long, the rice will dry out.
Once the rice is cool enough to handle, place a towel over it to prevent it from drying out.
Make Onigiri
Make the "tuna" mayo filling: Lightly mash chickpeas with a fork, then mix in vegan mayo and kombu dashi. Taste and add soy sauce as desired.
Make onigiri (see notes for plastic wrap method): Lightly wet your hands and dip the tips of one or two fingers in salt. Rub the salt over your hands. Place some rice in the palm of your hand and flatten.
Add tuna mayo filling to the center of the rice, leaving the edges free. Top with more rice to cover.
With lightly wet hands, pack the rice together and shape into a triangle. Rotate the onigiri as you press down the sides to form a triangle.
**If you aren't eating the onigiri right away, and you like crispy nori, then store the onigiri unwrapped and add nori just before eating.** Cut nori to fit just below the tip of the onigiri (or you can completely cover it). Place onigiri in the center of the nori and fold the nori over the rice.
To Store
If you aren't going to eat the onigiri right away, you will need to bring the onigiri to room temperature before storing. Place onigiri on a wooden chopping board or parchment paper-lined plate and cover with a towel - this will absorb excess moisture from the rice and prevent it from drying out.
Once cooled to room temperature, you can wrap it in plastic wrap or put in a bento box. Or, for a true combini experience, you can use onigiri wrappers*. Onigiri should be consumed within 6 hours.
Notes
Vegan Mayo: You can use my homemade mayo (add the sugar), vegan Kewpie mayo, or use regular vegan mayo and add a pinch of sugar.Shape with plastic wrap: If you use bare hands, some of the rice will stick to your hands and you will need to rewet them. You can use plastic wrap instead to make the process easier. Put a sheet of plastic wrap down on the counter and sprinkle with salt. Place rice in the center, top with filling and then cover with rice. Pick the plastic wrap up and pull the corners up to meet in the center over the rice. Place the onigiri in the palm of one hand and use the other hand to shape the onigiri.