Homemade Vegetable Sushi

Rinse sushi rice in cold water and drain. Place rice into a rice cooker and add 1 cup water. Seal and select setting according to manufacturer's instructions; cook until tender, about 15 minutes. Fluff with a fork and let sit for 10 minutes.

Pour rice vinegar onto rice and toss to coat. Let cool completely, about 30 minutes.

Cover a bamboo sushi mat in plastic wrap and place it on a cutting board. Place a sheet of nori on the covered sushi mat and cover it with cooled rice. Lay out 1/3 of the cucumber, carrot, and avocado on top, placing them across the bottom third of the sheet. Use the sushi mat to help roll the nori up. Repeat with remaining nori, rice, and vegetables. Use a sharp knife to cut each roll into 6 equal pieces.