Vegetable jalfrezi

INGREDIENTS

• 1 medium onion
• 1 fresh red chilli
• 1 thumb-sized piece fresh root ginger
• 2 cloves garlic
• 1 small bunch fresh coriander
• 2 red peppers
• 1 cauliflower
• 3 ripe tomatoes
• 1 small butternut squash
• 400 g tinned chickpeas
• groundnut or vegetable oil
• 1 knob butter
• ½ x 283 g jar Patak's jalfezi curry paste
• 2 x 400 g tinned chopped tomatoes
• 4 tablespoons balsamic vinegar
• sea salt
• freshly ground black pepper
• 2 lemons
• 200 g natural yoghurt