Dress the hot sushi rice with the vinegar, salt, sugar and mirin and leave to cool.
Place the nori sheet rough side up on a damp sushi mat. Wet your fingers so the rice doesn’t stick to them then spread over the nori pressing firmly and leaving a 5cm gap on the side furthest from you.
Place the wasabi, salmon and avocado on the closest edge. Using the mat to get started roll the sushi tightly to form a roll. Moisten the nori without the rice to help seal the roll, then carefully remove from the mat and refrigerate until needed.
Just before serving slice the rolls into 1 1/2cm slices. Serve with more wasabi, soy sauce and pickled ginger.