Add turmeric to the mutton or lamb and rub all over. Set aside.
Heat oil in a pressure cooker (electric or stovetop) and saute fennel seeds, bayleaf, cinnamon, cardamom and cloves for a minute. Add one green chilli, onions and ginger garlic paste. Cook this for 7-8 minutes till the onions are translucent.
Add tomatoes, coriander powder, meat masala and salt and cook for 5 minutes till the tomatoes break down slightly.
Add mutton, potatoes and two cups of water and put the lid on. If using a stovetop pressure cooker, cook on high pressure for 20-25 minutes (5-6 whistles). If using an electric pressure cooker or an instant pot, cook for 25 minutes and let pressure release naturally.
Once the pressure is released, open the lid and switch on the flame again. Add a little water if the gravy is too thick. Stir in garam masala, kasuri methi (if using), remaining green chillies, julienned ginger and ghee and simmer for another 3-4 minutes.
Check and adjust seasoning. Let the curry rest for 15 minutes before serving.
Any cut of lamb is good for this curry, but shoulder works best as it has the best flavour and tenderises really well
Meat masala is easily available at Indian stores. I use Lala's brand, Everest masalas are also highly recommended.
Kasuri Methiis dried fenugreek leaves that help round up the flavours in the dal makhani. Its available on amazon, and is used in many Indian recipes (on this blog), so stocking it won't be a waste
Don't skimp on the oil in the recipe. This is necessary for the masalas to fry properly as well as for the lamb pieces to toast well.
Feel free to adjust the spice levels based on your tastes by reducing or increasing the green chillies