Curry chicken and coconut milk bake

2 tbsp vegetable oil

4 skinless chicken breasts

2 onions, chopped

Finger-length piece ginger, grated

3 garlic cloves, crushed

2 tbsp medium curry powder

2 tsp ground coriander

2 tsp ground cumin

2 tsp mustard seeds

2 tsp white or red wine vinegar

2 tsp sugar (white or brown)

2 x 400g tins, chopped tomatoes

400ml light coconut milk (150ml will be used in the main dish and more will be needed for topping)

1 large red pepper, deseeded and cut into large chunks

1 large green pepper, deseeded and cut into large chunks

½ a small bunch coriander, leaves roughly chopped, stalks reserved

For the topping

1½ kg floury potatoes, cut into very large chunks

150ml light coconut milk

1 tsp turmeric

Juice 1 lemon

1 bunch spring onions, finely chopped

Stalks from ½ a small bunch coriander, finely chopped