1. Rinse the sushi rice until the water runs clear and place it with the cold water in a rice cooker. If you don't have a rice cooker, you can use a heavy pot.
2. When the rice is cooked remove the inner pot from the rice cooker and let it stand for five to ten minutes without lifting the lid.
3. After that stir the rice gently with a spatula and fan it until all the steam disappears. Add the vinegar, sugar, and sesame oil, and stir well.
4. Cover the insert with the lid and let the rice stand for 10 minutes more.
5. Place 1 nori sheet on the sushi mat, with the shiny side of the nori facing down. Using moist hands, spread a ball of rice over the nori sheet, covering it completely, except for 1-inch strip at the end.
6. Peel and slice the cucumber to strips.
Place a bunch of the sliced cucumber in the middle of the rice. Dip your fingers in water and wet the strip of nori that wasn't covered with rice. The reason for this is to close the seam at the end.
7. After you roll the sushi with your hands, wrap the bamboo mat around it and tighten it. Slice each cucumber sushi into ten pieces.
Check my other sushi recipes here, to find out how to make the same sushi roll with the inside-out (that means with the rice on the outside).