Place the rice in a sieve. Rinse under cold running water, to remove any excess starch, until water runs clear. Place rice and water in a large saucepan over high heat. Bring to the boil. Reduce heat to low; cook, covered, for 12 minutes or until all the water is absorbed. Remove from heat.

Combine the vinegar, sugar and salt in a small bowl. Transfer rice to a large glass bowl. Use a wooden paddle to break up rice lumps while gradually adding the vinegar mixture, gently folding to combine. Continue folding and fanning the rice for 15 minutes or until rice is cool.

Place nori sheets, shiny-side down, on a clean work surface. Using damp fingers, spread a quarter of the rice over each sheet. Arrange the smoked salmon, avocado and ginger evenly over 2 of the rice on 2 of the sheets.

Place remaining nori sheets over the salmon, rice-side down. Press down to secure. Cut each sheet into quarters. Cut each quarter in half diagonally, to create 2 triangles. Repeat with remaining sushi sandwiches. Serve with soy sauce and wasabi