1. Place the saffron and 2 tablespoons of the boiling water in a bowl, and soak for 10 minutes. Meanwhile, combine the rice and 3 cups of cold water in a saucepan and bring to a boil over high heat. Stirring often, boil briskly, uncovered,
2. In a heavy 4-quart casserole, heat 4 tablespoons of the ghee over moderate heat until a drop of water flicked into it splutters instantly. Add the cloves and cinnamon and stir for 30 seconds, then add the potatoes and, turning them constantly, fry for 5 to 6 minutes, or until they are golden brown.
3. Remove the casserole from the heat and sprinkle the potatoes with the mint and 1 tablespoon of the ginger. Spread half the rice on top, smoothing it flat. Combine the yoghurt and salt with the saffron and its soaking liquid, and pour half of it over the rice.
4. Sprinkle the yoghurt-covered rice with the remaining 1 tablespoon of ginger, the coriander and onions, then spread the rest of the rice over the top and pour in the remaining yoghurt mixture.
5. Carefully and slowly pour the rest of the melted ghee and the remaining 2 cups of boiling water down the sides of the casserole. Bring to a boil, cover tightly, and cook over high heat for 15 minutes, or until the rice is tender and has absorbed all the liquid in the casserole.
6. To unmold and serve the rice, run a long, sharp knife around the inside edges of the casserole. Place a heated serving plate upside down over the casserole and, grasping plate and casserole firmly together, invert them. Rap the plate on a table and the rice should slide out easily. Serve immediately.
