Cook the sushi rice according to package instructions, then let it cool slightly.
Mix the rice vinegar, sugar, and salt in a small bowl. Stir this mixture into the cooked rice until evenly seasoned.
Lay a piece of cling wrap over a bamboo sushi mat. Place one sheet of nori on top.
Spread an even layer of sushi rice over the nori, leaving about 1 inch at the top edge empty for sealing.
Layer desired fillings such as julienned carrots, cucumber, avocado slices, shrimp or tuna, and any optional sauces (mayonnaise or sriracha) horizontally across the center.
Using the bamboo mat as a guide, carefully roll the nori tightly to form a burrito shape.
Seal the edge by dabbing it with water and pressing gently.
Repeat the process with the remaining nori sheets and ingredients.
Use a sharp knife to slice the sushi burrito in half or serve it whole.
Notes
For variation, you can swap out the seafood for grilled chicken, tofu, or any protein of your choice. Serve with soy sauce, wasabi, or pickled ginger for extra flavor.