Preparation time: 10 minutes
Cooking time: 15 minutes

1 onion
2 pints stock
2 potatoes
2 bags watercress

Delicious served hot or cold, Liz Hurley swears by this healthy, low-fat soup, drinking up to 6 cups a day when she’s dieting. Sweat a chopped onion in a small amount of stock, then add 2 diced potatoes, seasoning and another 2 pints of stock. Bring to the boil and simmer until the potatoes are soft. Throw in 2 bags of watercress and stir for 3 minutes. Take off the heat and liquidize.