Wash rice, drain and put in rice cooker. Add salt and water then cook until it is done.
While the rice is still hot mash with wooden spoon then transfer the rice onto a rectangular dish and spread it evenly. Place another rectangular dish slightly smaller than the first on top of the rice to compress it. Weigh it down with heavy objects such as tins of food and leave overnight in refrigerator.
Cut the rice into 2 1/2 cm cubes and leave aside to serve.