There are many types of biryani, flavoured with spices and cooked with meat or vegetables. It is one of the great classics of the Indian kitchen. This recipe is a variation from my friend Janmejoy Sen, restaurant chef of the Imperial New Delhi. He says the secret of a good biryani is not only in the spices, but cooking the rice in two stages to keep it light and fluffy. A mint chutney completes a great dish and can be made in advance and kept in the fridge.