Dry roast the ingredients mentioned above at medium heat until the colour slightly changes and you get the aroma of roasted spices. Cool and grind to a fine powder.
Marinate mutton with the above roasted spices and all other ingredients mentioned above under marinade. Keep marinated mutton for at least 30 minutes.
Cook mutton in a pressure cooker adding little water. Keep aside. Add some oil in a pan and roast the coconut slices until the raw smell goes. Keep aside. Add oil to the same pan and splutter mustard seeds.
Add freshly torn curry leaves and saute till it turns crisp and gives out aroma. Add chopped onions/sliced shallots along with green chillies and saute till onions turn brown.
Add ginger garlic paste and saute till the raw smell goes. Add chopped tomatoes and cook till it turns mushy. Add chilly powder, turmeric powder, coriander powder, meat masala, salt and mix everything together and saute till raw smell of spices go.
Add cooked mutton along with water obtained from pressure cooking along with coconut slices. Mix everything well.
Increase heat to high and saute till the water has evaporated and dish turns dry. You'll need to keep stirring at intervals to prevent mutton from sticking to the bottom of the pan. When the dish has turned dry and the dish has turned dark brown, remove from heat. Serve hot with Appam/Idiappam/Steamed Rice with ghee.