This is a mild, aromatic curry, scented with the perfume of ginger, coriander and cardamom. What hotness it has comes from crushed black peppercorns, not the fiercer chilli peppers or powder.
Cut the lamb into 4cm/1½inch cubes. Mix well with the ginger and a little salt. Melt the butter in a pan and sweat the onions and garlic for 5 minutes. Slit the cardamom pods and extract the black seeds.