Before cooking the rice, rinse several times in running water until the water runs clear. Drain in a colander for about 1 hour. Cook on the stovetop or in an electric rice cooker according to package directions.
In a small saucepan over low heat, combine vinegar, sugar and salt. Stir gently to dissolve salt and sugar. Cool to room temperature.
While the rice is still warm, transfer to a large non-reactive bowl. Gradually drizzle the vinegar mixture over the rice, fanning the rice as you go. Use a rice paddle to mix gently without mashing the grains. Keep the rice covered with a damp cloth at room temperature until ready to make sushi. Do not refrigerate.