2 medium courgettes, cut into 1cm/陆in slices
1 yellow pepper, deseeded and cut into 4cm/1陆in chunks
1 red pepper, deseeded and cut into 4cm/1陆in chunks
1 orange pepper, deseeded and cut into 4cm/1陆in chunks
600g/1lb 5oz potatoes, preferably Maris Piper
1 medium red onion, halved and cut into thin wedges
freshly ground black pepper
1 tsp cumin seeds
1 tsp garam masala
1 tsp black mustard seeds
2 tbsp sunflower oil
陆 tsp turmeric