Tomato Soup

Serves 4 – 6 1 tsp olive oil 1 medium onion, chopped 1 medium carrot, chopped 1 celery stick, chopped 425g/14oz tinned chopped tomatoes 900ml/1 ½ pint chicken or vegetable stock 1 medium potato, chopped 2 tsp tomato puree Pinch of tarragon and salt and pepper 150ml/ ¼...