The process may be a bit long..but its very simple and quick if you can do both processes together
Pressure cook the meat with the below mentioned ingredients:
1 kg lamb / mutton (meat with bones)
1 large onion chopped
3 chillies slit
4 to 5 garlic cloves chopped roughly
3 bay leaves
5 to 6 pepper corns
3 to 4 cloves
3 cardamom pods split open
1.5 tsp salt
1 tsp haldi
Pressure cook the meat in a pressure cooker with the above ingredients until tender. You can discard the bay leaves and full spices. Keep aside to mix in your gravy mixture.
For the gravy
2 tbsp oil
4 large onions chopped finely
1 pod garlic chopped finely
2 green chillies slit
2 tbsp ground Kashmiri chilli paste
1 large tomato chopped
1 tbsp vinegar
Brown the onions well in oil. Add garlic and fry till garlic has cooked through or till it has turned lightly brown. Add chopped chillies and chilli paste and fry well for 5 to 10 minutes till the chilli paste is cooked and oil starts leaving the pan/dish. Add tomatoes and let it simmer till cooked. Add a little water if required to break down the tomatoes and to avoid burning. Once tomatoes are cooked add the vinegar.
Finally mix all the contents of your pressure cooker to this mixture and let it simmer on slow fire for 20 to 30 minutes to absorb the flavours. The gravy is usually a thick gravy and water may be added if required to make the gravy thin.