Heat the oil in a pan, add half the lamb and fry over a brisk heat until browned.|
Remove from the pan, add rest of the lamb and brown as well.
Remove and set aside.
Lower the heat, add the onion and sweet potato to the pan, and fry for 5 minutes, stirring occasionally.Return the lamb to the pan and stir in the curry paste and almonds.Stir until the lamb and vegetables are coated, then add the tomatoes and stock.
Cover and simmer for 45 minutes. Remove from the heat and stir in the yogurt. Season to taste, then reheat without boiling.
Serve garnished with the coriander, and accompanied by pilau rice and poppadums.