Hari Ghosht ki Phaal (Mutton in a coriander and green chillies gravy)

Ahhh..My first post.. I have agonized long and hard over this and couldn't decide what recipe I would put up...I am putting up a fairly easy lamb dish...a phaal as it is called.  This is a fail-proof recipe and a family favorite.

Hare Masale ki Phaal

Ingredients:
1/2 kg mutton
2 tsp ginger garlic paste
6 green chillis (or more, if u like more heat)
3 tsp black peppercorns
2  onions
1 small tomato (optional)
a bunch of coriander (naati..not the farm variety...)
1/4 tsp turmeric powder.
1 tbsp oil
Salt

Method:
Make a paste of green chillis, 1 onion, peppercorns, coriander, and tomato (optional).  Heat 1 tbsp oil in a pressure cooker.  Fry 1 chopped onion till light brown.  Add the lamb and 1 tsp of salt and mix well.  Cook on medium heat till the lamb is browned and all the water from the meat is absorbed.  Add the ginger-garlic paste and turmeric powder and stir well and fry for 2-3 minutes.  Add the green masala paste and mix well and cook for 2 more minutes.  Add a cup of water (approximately 100 mL) and pressure cook for 3 whistles.  Serve hot with chapatis or ghee rice.