Preheat the oven to 170 C, 160 Fan, Gas 3. Lightly toast the hot and fragrant rub mix in a dry frying pan or in the oven,
Chop the paste ingredients roughly, add to the rub mix and puree in a food processor.
Heat the butter in a large casserole pan and fry the curry paste mixture until golden, stirring often. Add the tomatoes and the stock or water. Bring to the boil, cover with foil and place in the oven for 90 minutes to intensify the flavours.
Remove the foil and continue to simmer on the stove until it thickens. This is your basic curry sauce.
Fry the lamb in a little olive oil until golden, then add to the curry sauce and simmer for about an hour or until tender.
Sprinkle with the chopped coriander and mint and stir in the yoghurt. Season to taste and add a good squeeze of lime juice before serving.