about 1/2 cup heavy cream or crème fraiche
oven to 400 degrees. Grease the bottom of a large roasting pan with 1/2
tbsp of the oil. Add the potatoes, leeks, scallions, and onions and top
with the thyme, salt and pepper. Drizzle the remaining oil over the top,
and stir to make sure the vegetables are thoroughly coated. Roast the
vegetables, stirring frequently, for 1 hour. Remove the roasting pan
from the oven and pour 6 cups of the stock or broth into the vegetables,
scraping up any browned bits. Working in batches, puree the mixture in a
food processor or blender until smooth.
soup to a medium-size saucepan. If the soup seems too thick, add another
1/2 cup to 2 cups of stock or broth, depending on how thick you like
your soup. Season to taste and heat over moderately low heat until
simmering. Just before serving, swirl the cream or creme fraiche into
each bowl if desired.
This soup is
a rich, multidimensional version of vichyssoise - the classic cold leek
and potato soup - filled with the flavor of roasted potatoes, leeks,
onions, and scallions. It is equally delicious hot or cold. For an extra
flourish, swirl a teaspoon of heavy cream or creme fraiche through the
soup just before serving. The soup is hearty enough to be served as a
main course, accompanied by a roasted pepper salad and crusty bread.