Take Vegetable oil in a deep pan. Once the oil is hot, add whole red chillies, black cardamom, whole black pepper, bay leaves, cloves and cinnamon sticks.
Saute them for 30 sec and add pinch of Asafoetida (as per taste) to it. Add chopped onions to it and saute them until onions turn golden brown in colour.
Now add chopped green chillies, garlic cloves and grated or diced ginger to it. Take care that the quantity of garlic and ginger is in equal proportion. Saute them for few minutes.
Now add chopped tomatoes and cook it until they become soft and meshed. If required add 1/4 cup of water to cook. If required cover it with a lid to speed up the process. If you are going to add potatoes, now is the time to add them.
Add all spices to the gravy mixture and cook it for two minutes.Add 2 - 3 cups of water and let it cook for 5 minutes.
Now add diced mutton pieces to the gravy and add Kasoori methi and few chopped Coriander leaves on top of it. Stir it and let it cook for 5 minutes. Add 2-3 cups water to it.
Now let it cook for 10 mins on high flame and 40 - 50 mins on medium flame. You can cover the pan with a lid to speed up cooking process. The amount of time required to cook Mutton will depend if the mutton is freshly cut and from young goat. If it is freshly cut and from young goat it will cook easily and in less time else it will take more time and maybe a bit chewy.
Use a fork to check if the mutton is cooked properly. If the mutton is tearing easily it is cooked. Turn down the flame.
Your tasty Mutton curry is ready to be served. Garnish it with chopped Coriander leaves and top it up with some Clarified butter and serve with Steamed rice (preferably Basmati Rice).
If you do not have Clarified butter, then top it up with Unsalted butter.