Jamie Oliver's vegetable jalfrezi

Serves 8

Ingredients:
* 1 medium onion
* 1 fresh red chilli
* A thumb-sized piece of fresh root ginger
* 2 cloves of garlic
* A small bunch of fresh coriander
* 2 red peppers
* 1 cauliflower
* 3 ripe tomatoes
* 1 small butternut squash
* 1 x 400g tin of chickpeas
* Groundnut or vegetable oil
* A knob of butter
* ½ a 283g jar of Patak's jalfrezi curry paste or Jamie's jalfrezi paste
* 1 x 400g tin of chopped tomatoes
* 4 tbsp balsamic vinegar
* Sea salt and freshly ground black pepper
* 2 lemons
* 200g natural yoghurt