Put the rice in a large bowl and wash it thoroughly, changing the water several times, until the water is clear. Drain and leave in the strainer for one hour. If short of time, soak the rice in clear cold water for 10–15 minutes, then drain.

Transfer to a deep, heavy-based saucepan, add 460 milliliters/two cups water and a piece of dried kelp (kombu), if using. Cover and bring to the boil over a high heat for about five minutes. Discard the kelp.

Lower the heat and simmer, covered, for about 10 minutes, or until all the water has been absorbed. Do not lift the lid. Remove from the heat and leave, still covered, for about 10–15 minutes.

Mix the rice vinegar, sugar and salt in a small jug/pitcher and stir until dissolved.

Transfer the cooked rice to a large, shallow dish or handai (Japanese wooden sumeshi tub). Sprinkle generously with the vinegar dressing.

Using a wooden spatula, fold the vinegar dressing into the rice. Do not stir. While folding, cool the rice quickly using a fan. Let the rice cool to body temperature before using to make sushi.