Cook the rice per instructions on the package. If using sushi rice and an Instant Pot, place the rice and water in the pot, set to “Low” Rice setting and release manually once done. Use a plastic or wooden spatula to mix in the seasoned rice vinegar. Leave the lid off to allow the rice to cool slightly.
To prepare the tofu, preheat oil on a nonstick skillet. Mix cornstarch with salt on a plate for dipping tofu in, set aside. Open and squeeze out excess water from the tofu. Slice into strips, thick enough so they can be handled without falling apart. Dip 2 sides of each strip into the cornstarch/salt mixture and place one of those coated sides down on the skillet. Repeat with all the pieces. Flip in a few minutes, once the edges are golden. Then remove from the skillet and allow to cool.
To assemble the sushi rolls, have the cucumbers, carrots, and avocados cut. Wrap a bamboo sushi rolling mat in plastic. Also, prepare a small dish with water off to the side.
Lay a nori sheet on the bamboo rolling mat, shiny side down. Spread a thin layer of rice, using a sturdy spatula to press the rice across half of the sheet. Lay out the tofu and veggies, staying away from the bottom edge (the part closest to you). Wet your fingers and run them along the top edge of nori so the sheet can secure closed. Roll using the bamboo mat, pressing everything firmly together (see video for a demonstration).
Serve as full sushi rolls or slice into small sections. Prepare a dipping sauce with tamari and wasabi, depending on your spice preference. Enjoy!