How to Make It
In a large bowl, rinse the rice in several changes of cold water until the water is thoroughly clear. In a medium saucepan, combine the rice with the 2 1/2 cups of water and bring to a boil. Cover and cook over low heat until all of the water is absorbed, about 15 minutes. Remove the rice from the heat and let stand, covered, for 15 minutes.
Transfer the warm rice to a bowl and stir in the sushi flavoring. Let the rice cool to room temperature.
Moisten your hands in the vinegar mixture and roll rounded tablespoons of the rice into balls, moistening with the vinegar mixture as you roll. Mash a few grains of rice onto one short edge of a nori strip; wrap the nori around a rice ball, using the mashed rice to seal the edges. Repeat to form the remaining balls. Sprinkle the balls with the sesame salt; serve.