Cut the seaweed (nori sheets) in two equal halves and place one half on the bamboo mat. Take 100g of cooked sushi rice and gently spread it across the nori sheet, leaving 1cm margin at the top of the nori and exceeding 1cm at the bottom.
Flip over the nori sheet with the 1cm margin of bare nori facing you.
Place the main ingredient in the middle of the nori, and then a second and a third (optional).
Roll the sushi roll using the bamboo rolling mat ensuring the filling is tucked in.
Release it, and trim either ends of the roll. Cut into 8 pieces with a sharp knife. Coat the roll with fried onions.
Serve with wasabi and sushi ginger on the side. Serve soy sauce separately in a small bowl.