Prepare the rice by rinsing it until water runs clear. In a pot, combine 2 cups cooked white short-grain rice with 2 tablespoons of rice vinegar and mix well.
Gently spread out each nori sheet on a bamboo sushi mat or clean kitchen towel dampened slightly (this will prevent sticking). Wet your hands lightly, pick up the prepared rice in small handfuls with wet fingers
place them at one end of the seaweed sheets and shape into an oblong loaf about 2 inches wide.
Using a sharp knife or sushi cutter, slice off bite-size pieces from each nori sheet. Arrange fish on top of half (or all) rice balls without completely covering them to maintain the visual appeal characteristic of nigiri style sushi.
Press lightly with your fingers so that they just touch and slightly stick together
this helps keep their shape intact when you eat them.