Soak the saffron in I tsp of hot milk for 5 minutes and crush to a paste. Boil the brains in water to which vinegar or lime-juice has been added. Then slice the brain into pieces. Grind together the ginger, garlic, onion and chillies. Heat the ghee and fry the whole spices. Now add the onion paste and fry, sprinkling a little milk now and then till the ghee floats to the top. Mix in the tomatoes and curd, along with the rest of the spices and salt, and cook till dry. Add the brains, mix well, and pour in 1 cup of water. Cook over a slow fire till the gravy turns thick. Remove from fire, place in a serving dish and sprinkle saffron on top. Serve garnished with fresh coriander leaves.