Pea & new potato curry

INGREDIENTS

• 1 tbsp vegetable oil
• 2 onions , sliced
• 3 red chillies , deseeded and finely sliced
• thumb-sized piece ginger , roughly chopped
• 2 tsp cumin seeds
• 1 tsp Madras curry powder
• ½ tsp turmeric
• 750g new potatoes , halved
• juice 1 lime
• 500ml pot natural yogurt
• small bunch coriander , stalks and leaves finely chopped
• 200-300ml vegetable stock , or pea stock (see tip, below)
• 300g podded fresh peas (or use frozen)
• lime wedges, to serve
• 2 naan bread , to serve