Peel the cucumber, cut off the ends, and cut it in half lengthwise. Use a small spoon to scoop out the seeds. Cut into thin strips about 1/8 inch wide. Set aside.

Lightly moisten your hands with water and grab about ½ cup of rice. Place it on one of the nori sheet halves and spread it out, leaving an inch at the top intact.

Dip your finger into the wasabi and spread it horizontally across the center of the rice. Sprinkle some toasted sesame seeds at this point.

Place the rice-covered nori on top of the bamboo mat an inch from the bottom.

Place several cucumber slices horizontally across the center of the rice. Make an even row about an inch wide and let the cucumber stick out on each side.

Roll the bottom edge of the bamboo mat over the rice nori, and filling, shaping it into a rectangular mound as you go. Make sure all the filling is enclosed.

Pull the mat back and lay it over the roll again. Roll it more tightly this time, applying even pressure and shaping the roll more firmly.

Now, place the mat over the roll and give it a final pressing to perfect it.

Repeat the whole process with the remaining 3 nori sheet halves.

Moisten your knife blade and slice the rolls in half, then into six equal pieces.

Serve your rolls on a platter with pickled ginger and soy sauce. Enjoy!