In a large mixing bowl, combine cooked rice, canned tuna, mayonnaise, and sesame oil. If using, stir in the chopped seaweed.

Taste and adjust the creaminess with more mayonnaise if desired, or add more rice if too wet. Let sit for about 5 minutes.

Divide the mixture into eight equal portions, flatten each in your palm, and roll into balls.

Serve immediately or refrigerate for 15-20 minutes for firmer consistency. Store in an airtight container if serving later.

Enjoy with dipping sauces like soy sauce or spicy mayo, alongside fresh veggies or a fruit salad.