Cook the rice

• Rinse the sushi rice until the water runs clear.
• Cook the rice with the water until tender and let it steam.

Season the rice

• Warm the rice vinegar with the sugar and salt until dissolved.
• Fold the seasoning into the rice and let it cool slightly.

Prepare the filling

• Mix the drained tuna with the mayonnaise.

Shape the onigiri

• Wet your hands and shape the rice into balls or triangles, pressing a hollow in the center.
• Fill with the tuna mixture and close the rice around it.
• Coat with sesame seeds and wrap each onigiri with a nori strip.