Place a small pan on medium heat and add the coriander seeds. When they become aromatic, after just a few minutes, remove them from the heat, allow to cool, and then grind them to a fine powder.
In a bowl large enough to contain all the chicken pieces, combine the ground coriander and the remaining marinade ingredients. Mix well, then add the chicken. Stir well to coat all the chicken pieces completely. Cover and set aside in a refrigerator to marinate overnight.
to prepare
Wash the rice in several changes of cold water until the water remains clear. Cover the rice with luke-warm water and set it aside to soak for at least 30 minutes. Drain when ready to start preparing the dish.
Warm the milk, then add the saffron threads. Mix gently, then set aside.
Bring a large pot with the water to a boil ready to cook the rice.
Heat the vegetable oil in a wide pan over medium-low heat. Add the onions and fry, stirring often, until they become deep golden brown. This may take up to 15 minutes. Remove with a slotted spoon and drain on a plate lined with absorbent paper. Set aside.
to cook
Add the cloves, cassia, green cardamom, bay leaves and cumin seeds to the pan and fry for one minute or until the spices sizzle.
Add the chicken and marinade to the pan and mix well. Increase the heat to medium-high and, stirring often, fry the mixture until it starts to colour, which will take about ten minutes. Be careful to prevent the yoghurt in the marinade from burning.
Add the tomatoes to the pan and sprinkle with salt. Mix well, reduce the heat and simmer the chicken and masala, uncovered, over medium heat for 20 minutes, or until the chicken is cooked through and the sauce is clinging to the chicken. Add as little water as possible to stop the sauce from sticking to the pan. Once cooked, set aside, and keep warm.
Whilst the chicken is cooking, drain the soaked rice and put it into the pot of boiling water. Add the salt, return to the boil, then reduce heat to a simmer and cook for five minutes, or until the rice is just tender but still firm. Remove from heat and drain well
Assemble the biryani straight away while the rice is still hot. You will want to get five layers - rice, chicken, rice, chicken, rice. First, put three tablespoons of water and half of the ghee into a deep, heavy-based cooking pot or casserole, then spoon in a third of the rice. Sprinkle over about a third of the saffron milk and rosewater, then spread with half of the chicken mixture and a third of the fried onions.
Add another third of the rice and repeat as above, using the rest of the chicken. Top with the remaining rice and splash with the remaining saffron milk and rosewater. Drizzle the remaining ghee around the edges of the rice so that it drips down the inside of the pan.
Cover with a well-fitting lid. Put over high heat to get the ghee hot and some steam rising – lift up the lid to check. As soon as you see steam rising, turn down to very low and cook for 25 minutes.
Place a small pan on medium heat and add the pistachios and cashews, then gently toast until they start to colour. Remove from the heat and set aside.
Turn off the heat and stand the biryani, still covered, for five minutes.
to serve
Turn the biryani out onto a large serving platter. Scrape the bottom of the pan to collect the crusty golden pieces from the bottom. Scatter with the rest of the crisp onions and the toasted cashews and pistachios. Garnish with the coriander sprig and serve.
notes
Sella rice is parboiled rice, available from Indian grocers. If unavailable basmati rice can be substituted. Note that you may need to reduce the rice cooking time.
300g of uncooked rice is approximately 1½ cups.
The bottom of the pan will contain crusty, golden fried pieces of rice. These are an important part of the dish and should be used. However, if you have cooked on too high a temperature these will appear dark brown and are probably burnt, so should be discarded.