Seafood Maki Sushi with Salmon and Mackerel

Method

The salmon and mackerel must be frozen for at least 24 hours before being eaten raw.
Mix sugar, salt, and rice vinegar in a small saucepan, and bring gently to a boil while stirring. When the sugar and salt are dissolved, the rice marinade is ready. Let the marinade cool before use.
Cook the rice as described in the recipe sushi rice explains, or follow the instructions on the package. Transfer the rice to a dish, add some of the marinade and gently fold it in. The rice must not become too wet, so add a little at a time. Let the rice cool to room temperature.
Slice the trout and mackerel into thin slices, cut the avocado and cucumber into strips about 1 cm thick, and finely slice the spring onion. Cut the nori sheet in half.
Cover the bamboo sushi mat with plastic wrap. Mix water with a little rice vinegar, and lightly wet your hands so the rice doesn't stick. Place half a nori sheet on the bamboo mat with the rough side up, spread a layer of rice over the entire sheet and flip so the rice is on the outside.
Arrange avocado, cucumber and spring onion along the bottom edge of the sheet. Roll it up, then lay slices of trout and mackerel across the roll so it is covered with fish. Alternate trout and mackerel to create a rainbow effect. Cut each roll in two, then cut those pieces in two again until you have 8 pieces.
Serve the sushi pieces with soy sauce, wasabi, and pickled ginger.