Lay the bamboo sushi rolling mat on a clean surface. Optionally, cover the mat with plastic wrap for easier rolling and cleanup if you are using a bamboo mat and not a silicone mat.
Place a nori sheet shiny side down on the sushi mat.
Lightly brush the rough side of the nori with soy sauce using a small brush or spoon. This will add an extra layer of flavor to your rolls.
Wet your fingers with water to prevent sticking, then spread a thin layer of sushi rice evenly over the nori, leaving about 1 inch of space at the top edge of the nori for sealing.
Place a few slices of avocado, cucumber, and carrot horizontally across the center of the rice.
Lightly drizzle sriracha sauce over the fillings for an extra kick of heat.
Lift the edge of the sushi mat closest to you and start rolling the nori over the fillings, using your fingers to keep the fillings in place as you roll. Press gently but firmly as you roll to ensure a tight, even roll.
When you reach the edge of the rice, wet the exposed strip of nori at the top with a little water to seal the roll.
Transfer the roll to a cutting board. Use a sharp knife to slice the roll into 6-8 pieces. Wipe the knife with a damp cloth between cuts to ensure clean slices.