In a food processor, blend together the garlic, onion, ginger, all of the ground spices, salt and tomato purée.
Heat the oil or ghee in a large saucepan or flameproof casserole and add the lamb pieces and cardamom pods. Quickly fry until the lamb is browned all over. This may need to be done in 2 batches, depending on the size of your pan. Stir in the spicy paste and cook for about 5 minutes, stirring frequently. Pour in the lager and bring to a simmer. Cover with a lid and cook for about 1-1¼ hours, stirring occasionally, until the sauce has thickened and the lamb is lovely and tender. Leave the dish to relax for 5 minutes before serving.