Place mutton in a bowl. Add ground turmeric. Toss to coat. Season with salt. Marinate for about 1-2 hours in the refrigerator., if time permits.
Place meat in a large pan. Add water. Place the pan over medium-high heat. Cover and cook for about 45 minutes or until cooked through, adding more water if required.
Alternatively, you can cook meat in the instant pot or stovetop pressure cooker.
Place a small frying pan over low heat. Add coriander seeds, black peppercorns, fennel seeds, cumin seeds, cinnamon stick, cloves, cardamom pods and red chilies. Fry, stirring, for about 2-3 minutes or until the spices are aromatic and get a light brown color. Remove from heat. Leave to cool completely.
Transfer spices to a food processor. Process to a fine powder. Set aside.
Meanwhile, heat oil in a large frying pan over medium-high heat.
Add shallots, ginger, garlic, green chilies and curry leaves. Sauté, stirring occasionally, for about 2-3 minutes or until the shallots start to turn brown.
Add cooked mutton with water and ghee (if using).
Add ground spices. Season with salt. Stir fry for about 3-4 minutes or until most of the water is absorbed and the sauce is thick.
Add coriander (cilantro) leaves. Stir to combine.
Garnish with curry leaves and cashew nuts (if using).
Serve with your favorite flatbread or rice.