Cut the nori seaweed into halves, and then place half of the nori on the sushi mat shiny side down. As a golden rule, the shiny side of the nori seaweed should always be on the outside of the sushi.
Place roughly 110g of sushi rice on the nori seaweed and spread across evenly. Flip the nori seaweed and sushi rice so that the nori seaweed is facing upward. Add a small portion of mayo, carrot, cucumber, tuna or any other filling in the centre.
Start rolling from the bottom, tucking the edge of the roll to fully enclose the filling. Lift the edge of the mat and continue to roll forward until the sushi is formed into a firm cylinder.
Slightly wet the blade of a sharp knife and slice the roll into 6 pieces. First, slice it into halves and then the halves into thirds. Clean the knife with a wet towel between cuts to prevent the rice from sticking to the knife.
Serve with soy sauce. Feel free to garnish with other foods such as sesame seeds, tobiko, chives, etc.