Heat 1/4-cup of oil in a pan and fry the onions until golden. Add the cashew nuts and fry until brown. Remove the onions and cashew nuts from the oil and set aside to cool. Then grind them to a paste.
In the remaining 1/4-cup of oil fry the cinnamon, green chili, ginger, garlic for couple of minutes. Add lamb, coriander powder, salt and half of the garam masala powder. Stir constantly. Add red chili powder and the yoghurt. Stir continuously for 5 minutes on a low heat. Then let it cook until the yoghurt is absorbed. Add the ground onion-cashew nut mixture and mix well. Then add the cardamom, mace powder and remaining half of the garam masala powder. Fry for 3-5 more minutes. Pour 4 cups of water and cook until the lamb is tender and fully cooked. Stir in the lime juice and soaked saffron to the lamb mixture and serve hot.