Put the rice in a large bowl and wash it thoroughly, changes the water several times until the water gets clear appearance. Strain it and keep it strainer for one hour. Or we can soak the in cold and clear water for 10 to 12 minutes.
Put the rice into heavy bottom deep pan, add 4 cup of water and dried kelp (if using) and cover it with lid and bring to boil on high heat for approx 5 minutes then discard the kelp.
Lower the heat and cover, for approx 10 minutes or until the water is being absorbed. Do not lift the lid and let it be covered, keep aside from stove for 15 minutes.
Mix the rice vinegar, sugar and salt in a small bowl and stir until dissolved.
Transfer the cooked to a large bowl or food pan and sprinkle the vinegar mixture on top of it.
Using wooden spatula, fold the vinegar dressing into the rice. Do not stir fold it very generously, while folding cool the rice quickly using a fan. Cool the rice to body temperature before using it for sushi.