Place nori on bamboo mat. Wet fingers with dipping water, and add 3/4 cup of sushi ice over the nori in an even layer. Next, sprinkle a tbsp. of sesame seeds over the rice. Leave a 1/2 inch border around nori.
Spoon half the tuna mixture over the bottom third of the nori.
Grip the edge of the bamboo mat and roll it forward.
Remove roll from mat and slice in one-inch pieces.