Stir the rice vinegar into the prepared sushi rice.
Slice vegetables into thin strips.
Place one nori sheet on a work surface
Spread 1/8 of the rice in a thin layer, over the bottom third of the sheet.
Place 2 strips of sweet potato, avocado, and cucumber, extending the width of the nori sheet.
Gently lift the bottom end of the nori sheet and roll it up over the rice and filling, as you would roll a tortilla. Roll slowly and tightly.
When you are about 2.5 cm from the end, lightly moisten the remaining nori with a few drops of water and continue rolling to seal.
Set aside, seam side down, and repeat with the remaining sheets and fillings.
Slice each roll into pieces 5 cm wide and enjoy!
