For the saffron rice, heat the oil in a large, deep iron pan, sauté the diced onion until translucent, add the rice and stir constantly to coat the rice grains with the oil.
The rice must not turn brown! Add boiling water, salt and saffron and bring the rice to a boil while stirring.
Over low heat and with the lid closed, cook the rice quietly for about 20-30 minutes until all the liquid is absorbed. The rice will still have a slight bite to it.