In a small bowl, combine the rice vinegar, sugar, and salt then stir well.
Place in a microwave oven for about 10 seconds then stir again so that all the ingredients will be dissolved.
Pour the vinegar-sugar-salt mixture on the sushi rice then mix well. Set aside.
Cut the sushinori (nori) in half crosswise.
Lay one sushinori (shiny side down) on a flat surface
Scoop some sushi rice and spread over the sushinori (make sure to distribute the rice evenly)
Sprinkle sesame seeds on top of the sushi rice
Cover the mat (or bamboo mat) with plastic (such as cling wrap)
Place the mat on a flat surface then put the sushinori with rice over the mat. The part that has the rice should be facing down.
Arrange the crabstick, cucumber, and avocado in the center of the sheet
Grab the edge of the mat, keeping the fillings in place with your fingers, and roll it into a tight cylinder, using the mat to shape the cylinder. Set aside.
Continue doing the process until all the rice are used.
Trim the edge of the rolled sushi then cut the cylinder in half using a sharp knife
Slice each half crosswise into three equal pieces.
Place in a serving plate then serve with soysauce and wasabi. Share and enjoy!