Start by rinsing sushi rice under cold water until it runs clear, then combine it with water in a pot. Bring to a boil, cover, and simmer for 15 minutes until tender. Let it cool for 10 minutes.

In a large bowl, combine cooled sushi rice with drained tuna, mayonnaise, and sesame oil. Mix in torn nori until well combined.

Wet hands and scoop about ¼ cup of the mixture, shaping it into triangular or round rice balls.

Serve immediately with a side of soy sauce, or store in an airtight container in the fridge for up to 2 days.