Pressure cook the mutton pieces, onion, tomato, ginger garlic paste, turmeric powder, chilli powder, coriander powder, pepper powder and salt for 7 to 8 whistles.
Now take a pan and heat with oil.
Add mustard seeds and curry leaves.
Then add the pressure cooked mutton pieces.
Stir well.
Close with a lid and cook till the mutton pieces would be in dry form.
In-between stir well.
Finally garnish with coriander leaves and serve hot.