Heat the oil in a large non-stick pan, season the lamb and brown for 3-4 minutes. Remove from pan and set aside.
Add the onion, garlic, ginger and spices to the same saucepan and cook for 2 minutes. Sprinkle on the flour, stir for 1 minute, then add 250ml water. Stir again, then return the meat to the pan with the bay leaf.
Cover, reduce the heat and simmer for 1½ hours.
Remove from the heat and add the spinach. Stir until wilted. Add the yogurt and adjust the seasoning.