Curried vegetable soup

1) Heat the oil gently in a large saucepan, add all of the ingredients except the stock.
2) Sweat everything gently for 10-15 minutes, stirring to ensure ingredients are coated in the oil. Season to taste.
3) Add 1litre of the stock, bring up to the boil then turn down to a simmer for 20 minutes or until vegetables are tender.
4) Allow to cool and transfer to a blender and liquidise in batches.
5) Return to the pan and thin down with reserved stock if necessary. Check seasoning.
6) Reheat and serve.