Wash the rice and spread it out on a flat board to dry. When completely dry, crush to a third of the size of the grain. Boil the milk and allow it to thicken, stirring constantly. When it is reduced to three-quarters of the original quantity, add the rice and cook for a few minutes. Add sugar and sultanas, and cook until you have a thick custard (10 to 15 minutes). Remove from heat and flavor to taste with rose water or vanilla. Sprinkle with pistachio nuts. Serve hot or cold.