Serves 6

5 tbsp vegetable oil
7 black peppercorns, left whole
3 black cardamom pods, left whole
5 green cardamom pods, left whole
4 cloves, left whole
1 cinnamon stick
1 piece of mace
1 onion, finely chopped
750g/1½lb lamb or mutton, cut into pieces
6 garlic cloves, peeled, left whole
2cm/¾in piece ginger, peeled and cut in half
2 tsp ground coriander
2 tsp ground cumin
½ tsp red chilli powder
2 tsp ground fennel seeds
1½ tsp garam masala
salt, to taste
2 tomatoes, blended to a pulp in a food processor
3 tbsp plain yoghurt, stirred
handful chopped fresh coriander, leaves and stalks