Melt the butter with the oil in a frying pan on the hob and fry the diced lamb until browned. Transfer to a casserole dish.
Add the onion to the pan and fry gently for 5 minutes. Stir in the garlic and spices. Season with salt and fry for a further 2 minutes. Stir in the measurement water and bring just to the boil. Pour over the lamb. Place on the lower rack of the halogen oven.
Set the temperature to 200°C (392°F) and cook for 20 minutes until the lamb is tender, stirring twice. Serve with basmati rice, garnished with finely chopped coriander.