Wash the mutton pieces and pat them dry. In a large bowl, mix yoghurt, ginger-garlic paste, red chilli powder, turmeric and salt. Add the mutton and coat well. Cover and leave to marinate for at least one hour.
Heat mustard oil or ghee in a heavy-bottomed handi on medium flame. Add cumin seeds, green cardamoms, cloves, black cardamom, cinnamon and bay leaves. Let them release their aroma for a few seconds.
Add the sliced onions and cook on medium heat until they turn golden brown. Stir regularly so they colour evenly.
Add the marinated mutton along with all the marinade. Cook on medium-high heat for 8–10 minutes, stirring often, until the raw smell of the yoghurt and spices goes away and the meat starts to change colour.
Lower the flame. Add coriander powder, green chillies and salt if needed. Mix well.
Pour in 1 to 1½ cups of water, just enough to create a light gravy. Cover the handi with a tight lid and cook on low heat for 50–60 minutes. Stir once or twice in between. The mutton should become soft, and the oil should begin to separate.
Sprinkle garam masala and mix gently. Cook uncovered for another 5–7 minutes so the gravy thickens slightly.
Turn off the heat. Garnish with fresh coriander leaves. Let the Home Style Ranjha Gosht rest for 10 minutes before serving.