142 g (5 oz) carton natural yogurt
5 ml (1 tsp) garam marsala
5 ml (1 tsp) ground cumin seed
1.25 ml (1/4 tsp) ground coriander
1.25 ml (1/4 tsp) ground turmeric
1.25 ml (1/4 tsp) freshly ground nutmeg
2.5 ml (1/2 tsp) garlic powder
2.5 ml (1/2 tsp) chilli seasoning
juice and finely grated rind of 1 lemon
450 g (1 lb) lean lamb fillet, cubed
8-12 button onions, skinned
1 small green pepper, seeded and cut into 2.5 cm (1 inch) squares
175 g (6 oz) button mushrooms, wiped
lemon wedges, to garnish