4 to 6 servings
Vichyssoise, an American adaptation of a French country soup, is the invention of Louis Diat, who created it to celebrate the opening of the roof garden at the old Ritz Carlton Hotel in New York. This is a nice soup to serve on a hot summer day.
Very thinly slice white and very light green parts of leeks; discard remaining parts of leeks. In a large heavy saucepan, melt butter over low heat; increase heat to moderate, add leeks or onion, and sauté, stirring frequently, until tender but not browned. Add potatoes, chicken broth, bay leaf, and salt and pepper to taste. Bring mixture to a simmer, cover, and continue simmering for until potatoes are just tender. Remove enough potatoes to cut into 1 cup very very small cubes and reserve. Continue cooking remaining potatoes until very tender. Remove bay leaf pieces and discard.
Pour half of remaining potato mixture into a blender container; cover and blend at medium speed until smooth. Add remaining potato mixture to blender, cover, and continue blending at medium speed until smooth. Return mixture to saucepan and stir in half-and-half or half-and-half and milk. Transfer mixture to a bowl or other container, stir in reserved potato cubes, cover, and chill thoroughly in the refrigerator. Stir in cream just before serving.
To serve, ladle soup into chilled soup cups or bowls, dividing evenly. Garnish each serving with minced chives or parsley and a sprig of watercress. May also garnish each with a sprinkle of paprika, if desired.
Note: May omit half-and-half and cream, if desired. Use reduced-fat or skim milk in place of half-and-half and cream; however, the flavor will not be as rich..