Chop sashimi/sushi grade tuna and mix with mayonnaise and ichimi-togarashi. Put a nori sheet on top of a bamboo mat. Spread a quarter portion of sushi rice on top of the nori sheet. Sprinkle sesame seed on top of the sushi rice. Place a quarter portion of tuna mixture lengthwise on the rice. Roll up the bamboo mat, pressing forward to shape the sushi into a cylinder. Press the bamboo mat firmly and remove it from the sushi. Make more rolls. Wipe a knife with a wet cloth before slicing sushi. Cut the rolled sushi into bite-sized pieces.
Makes 4 rolls