Preheat the oven to 240°C/475°F/Gas Mark 9. Mix together the minced mutton, mutton fat, onion, green chillies and fresh coriander. Grind to a fine consistency. Add the rest of the ingredients except the oil and mix well. Divide the mixture into twelve equal portions. Pat the mince mixture with moist hands onto skewers and shape into kababs.
Cook the kababs in the oven or in a hot tandoor till almost done. Baste with butter or oil and continue to cook till completely done. Sprinkle with a little chaat masala and lemon juice and serve hot with Mint Chutney.