1. Trim Lamb and cut into 4 cm (1½ inch) cubes. Cut potatoes into 2 cm (¼ inch) dice. Heat oil and fry potatoes until well coloured. Remove and drain well.
Slice onions thinly. Grind seasonings from cardamoms to chilies to a fairly smooth paste and rub into the meat cubes. Place in a dish and pour on yogurt. Leave for 2 hours to marinate.
ghee and fry lamb until well colored. Add any remaining marinade, sliced
onions and cover with water. Bring to the boil, cover and simmer until
meat is very tender.
4. Add fried potatoes and mustard seeds and season with chili powder, salt, pepper and garam masala to taste. Heat through. Transfer to a serving dish and garnish with chopped coriander leaves.