Mix the ginger, garlic, garam masala, turmeric, 1 tsp salt and cardamom with the yoghurt and chicken. Marinate for 3 hours. Bring the milk to the boil and pour over the saffron. Heat the oil in a pan and fry the onions until golden brown. Remove half of the onions and set aside. Cook the rice with the cumin, cinnamon and peppercorns until half done. Drain and mix in a bowl with the remaining salt. Finely chop the chillies. Add the chicken mixture to the onions in the pot. Add half of the saffron milk and half of the chillies, parsley and lemon juice. Add the rice and the rest of the ingredients. Cover and cook over a low heat for about one hour.