Wash and soak the rice for 20 minutes in cold water.
Mix all the ingredients for the marinade together, spread over the chicken thighs and set aside for 15–30 minutes.
Meanwhile, soak the saffron in the milk for three to five minutes, then mix in the ghee and rosewater.
In a large casserole simmer the chicken for the biryani about 20 minutes until tender (add half a cup of water if it seems too dry).
Slice the onions and shallow fry on medium heat in some rapeseed oil until brown, drain. Just remember that the onions will keep on cooking after you remove it from the oil, so take them out when just golden, if not, the fried onions will be burnt.
Bring the whole spices and salt to the boil in 1.5 litres of water, reduce the heat and simmer for five minutes or so.
Add the drained rice and boil for about eight to nine minutes – the rice should be 80–85 per cent cooked. At this point, the rice is just tender but not quite cooked through. I like to use a good quality basmati rice as this gives the best result. Succlent grains of rice where you can see each individual grain.
Drain the rice and layer t over the marinated cooked chicken in your heavy duty cast iron pot.
Sprinkle the reserved handful of chopped mint and the soaked saffron mix over the rice and cover the casserole with a lid.
Heat the chicken biryani on a low flame for five to seven minutes until the rice is completely cooked and remove from heat.
Sprinkle the fried onions on top before serving.
Leave it to rest for five minutes and serve with a raita of your choice.