Put 2 ozs. of butter in a saucepan and, when hot, fry the sliced onions to a golden brown. Then add the rice, with the rest of the butter, and cook till the rice has absorbed most of the butter, stirring frequently. Then add the other ingredients and just cover with hot water. Put the lid on the saucepan and simmer very gently till the rice is tender. Remove the rice from the saucepan, put in the oven so that the moisture will evaporate, and 10 minutes before serving sprinkle with a little saffron.