method

1. Heat a soup pot over medium heat and add olive oil. Saute leeks until soft, about 5 minutes. Add potatoes, chicken stock and thyme, cover loosely and simmer until potatoes are tender, about 20 minutes.
2. Remove from heat and purée. Strain soup, then cool to room temperature and chill completely, about 3 hours. Stir in cream and season to taste. Garnish soup with chopped chives.