Open the can mutton and remove the meat. Place on a plate and microwave for a minute, until the fat melts. Set aside on another plate lined with paper towels to absorb the extra fat.
Wash, peel and cut potatoes into 1inch cubes.
Peel and crush ginger, garlic and chillies to a paste.
Peel and thinly slice onion.
On medium heat, add oil in a frying pan. When oil is hot add mustard and cumin seeds; fry until fragrant and sizzling.
Add sliced onions and saute until just soft and translucent. Add garlic,ginger chilli paste, curry leaves and saute until fragrant, about a minute.
Next add the potatoes, turmeric and masala; stir well and cook covered for 2-3 minutes, stirring once or twice.
Add salt to taste, hot water, stir well and cook covered for about 8 minutes until the potatoes are cooked through and the sauce has thickened.
Finally add drained corned mutton. Stir well and heat through for 5mins.
Garnish with coriander and serve with roti.