Make the Rice: Wash rice well by rinsing 2 to 3 times without breaking the rice. Cook the rice a rice cooker according the manufacturer¿s instructions. While the rice is still hot, transfer it to a bowl and add the vinegar. Using a rubber spatula or wooden paddle, mix the rice until well coated with the vinegar, slightly cooled and glossy, about 5 to 6 minutes. Transfer the rice to a parchment paper-lined sheet pan, cover with a tea towel, and let cool for 30 minutes.
To make the Filling: Finely chop the tuna and transfer to a bowl. In another bowl, whisk together the mayonnaise and Sriracha (add more Sriracha, if desired). Gently mix together the tuna and mayonnaise mixture.
To make the Sushi Roll: Fold the nori sheets in 1/2 and break them apart. Working with 1/2 a sheet at a time, lay it on the bamboo mat shiny side-down. Spread an even layer of rice (not too thick) on the nori, and sprinkle lightly with the sesame seeds. Flip the nori over, and arrange the tuna mixture across the middle of the sheet, forming a horizontal line. Put about 20 pieces of kaiware evenly on top of the tuna line (make sure the sprouted ends face towards the ends of the roll, jutting out from the sides). Roll the nori over the tuna by lifting the near end over the top and rolling to meet the far end; then use the sushi mat to press the roll together. Repeat to make 4 rolls.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.