Heat oil in a kadai or pan. Add the curry leaves and give a stir. Add the cut green chillies & again stir.
Now add the sliced onions and fry on medium heat for 10 mins till light brown.
Add the strained boiled mutton pieces (without the stock) and mix & fry on high heat for around 2 mins.
Add the Red Chilli powder, mix & fry on medium heat for 1 min.
Now add the mutton stock and mix & fry on high heat for 7-8 mins. Fry till the liquid nearly dries up.
Add the coriander, fennel, Garam masala powders & crushed pepper, mix and add a splash of water (2 tbsp).
Fry on medium heat for 3-4 mins till the masala coats the mutton pieces well.