Marinate the mutton pieces with curd, turmeric powder, coriander powder, red chilli powder and ginger paste for at least 1-2 hours.
Now fry the potato pieces with salt and turmeric powder, then keep it aside.
Heat mustard oil along with two teaspoon of desi ghee in a pan. Season the oil with bay leaf, dry red chilli and whole garam masalas.
Then add onion slices for frying. Addition of a little salt and sugar will also help to give a nice color and make the onions translucent.
After frying the onion slices for sometime, add ginger-garlic and green chilli paste.Cook this well till the spices start to give a nice aroma.
Now its time to add the marinated mutton pieces and cook while covering with a lid.
When one side of the mutton has changed color, turn the other side and cook again while covering with a lid.
Next add the remaining coriander powder, red chilli powder and turmeric powder. Stir it and add the tomato paste into the gravy, this gives a nice color to the curry. Balance the sourness by adding sugar.
As mutton takes time to cook, we will use pressure cook this dish. Before pouring the curry into the cooker, we shall add the fried potato pieces with enough water, also adjust the salt taste of the gravy.
Cover the cooker lid and cook in a medium flame until 3 to 4 whistles blow. (Do not open the lid immediately by force releasing the pressure.)