Cook rice. While cooking, combine the vinegar, sugar, and salt in a pan, heat on low until sugar and salt dissolve, and set aside.
As soon as the rice is done, fluff with a rice paddle making slicing motions, and sprinkle over as much sushi vinegar as desired. Mix through with slicing motions of your rice paddle.
On a sushi mat, lay out a slice of nori. Cover in an even layer of rice, leaving the final inch furthest from you free of rice. Lay down slices of cucumbers, and then roll tightly, using the sushi mat to guide your actions.
Repeat with remaining ingredients, adding in avocado as desired for a creamy taste on the original cucumber roll.
Slice all rolls with a sharp knife, and enjoy with wasabi and soy sauce.