| 1 | Cut the leeks in half lengthwise and then crosswise into thin slices. |
| 2 | Place in a colander and run under warm water to remove all traces of sand. |
| 3 | Drain and set aside. |
| 4 | In a large casserole, melt the butter over low heat. |
| 5 | Add the flour and cook, stirring constantly for one minute without browning. |
| 6 | Add the chicken stock and whisk until well blended. |
| 7 | Add the reserved leeks, carrots, turnips, parsnips and potatoes. |
| 8 | Bring to a boil, reduce heat and simmer until the vegetables are almost tender. |
| 9 | Add the lettuce and spinach leaves to the soup, and season with salt and pepper. |
| 10 | The lettuce should just wilt, but still remain crisp. |
| 11 | Do not overcook. |
| 12 | Before serving, add the heavy cream and heat the soup through without letting it come to a boil. |
| 13 | Transfer the soup to a large tureen, sprinkle with chives and parsley and serve hot with thin slices of black bread. |