Rinse the sushi rice until the water runs clear (this could take 3-4 rinses). Completely drain the rice and then place in a saucepan.

Add 1 ½ cups water to the rice and bring the water to a boil over medium to high heat. Once at a boil, reduce the heat to low, gently stir, and cover with a lid. Cook for 15 minutes. Remove from heat and allow to rest for 15 minutes covered.

Transfer the rice to a glass mixing bowl. Break up the rice using a wooden spoon and gently mix through the vinegar, sugar, and salt. Allow the rice to cool completely. Once cool, cover with a damp tea towel and place in the fridge for 5 to 10 minutes.

In a medium sized bowl, combine the drained canned tuna, Japanese mayonnaise, Sriracha sauce, soy sauce, chopped green onions, and salt and pepper. Set aside.

Cut the longer side of the nori (seaweed sheets) in half. Most seaweed sheets are using 21 cm x 19cm or 8.27 inches x 7.48 inches).

Place a cut nori sheet on a bamboo rolling mat shiny side down.

Wet your fingers with water. Spread ½ cup (100 grams, 3.53 ounces) of cooked sushi rice in the centre of the rice., leaving at least 1.5 cm (0.6 inches) at the top of the seaweed.

Place some of the tuna filling in a thin row along the middle of the rice.

Wet your fingers lightly and wet the top edge of the nori sheet.

Placing your fingers on top of your filling, lift the edges of the bamboo rolling mat with your thumbs.