Clean and cut lamb into 1 inch pieces. Put to boil with 1.5 litres/5 cups of water, turmeric and salt. Reduce heat and simmer till lamb is tender. Remove pieces and reserve stock. Smoke mustard oil in a pan, reduce flame and add the other cooking oil. Add whole red chilies and sauté till chilies turn black, then discard the chilies.
Crackle mustard seeds, cloves and asafetida in the oil. Add the lamb pieces, red chili powder, cumin seeds, nigella, jaggery, ginger and garlic and stir.
Cook till the meat pieces turn brown. Stir in stock and lemon juice and simmer for 2 minutes. Reduce flame and stir in the yogurt stirring vigorously. Cook till the fat surfaces.
Serve with naan or paratha. Garnish with deep fried onion rings, if desired.