Preheat the oven to 180ºC (160ºC fan).
Add the ghee or olive oil to a small oven proof pan and heat over a medium heat. Add the onion and fry for 5-6 minutes until soft. Add in the grated ginger, garlic and chilli along with the cumin and garam masala and fry for 2-3 minutes until fragrant.
Add the potato and a splash of water and let that cook for 5 minutes or so until the potato starts to soften.
Add in the lamb mince and cook until it starts to brown then add in the flour and tomato purée and mix until combined. Add in the stock, water, peas and fresh coriander and simmer for around 5 minutes until its thickens slightly. Taste and season with salt and pepper then take off the heat while you prep the pastry.
Cut the sheets of filo in half then brush each half with melted ghee or butter. Scrunch up then place on top of the pie. Bake for 25-30 minutes until golden and crisp.
