Season lamb and leave to stand
Heat oil and cook lamb in batches, until well browned on all sides. Set aside on plate.
Add onions and cook about 8 minutes, stirring.
Add garlic and ginger and cook 2 minutes.
Add tomato and seasonings, cook till fragrant, about 2 minutes.
Return lamb to the pot with any juices.
Add raisins and 4 c water. Bring to a boil and simmer gently for an hour.
Remove the lid and cook until the lamb is tender and sauce has reduced a thickened, 15-30 minutes more.
Serve with couscous and garnish with cilantro.