Trim and clean leeks (see below); thinly slice the white portion.
Cut and clean leeks - You need to thoroughly clean a leek because dirt can become trapped in its many layers. Trim the root portion right above the base (cutting too far up the stalk will remove the part that holds the layers together). Slice off the fibrous green tops, leaving only the white-to-light green stalk; discard greens. Cut the leek in half lengthwise, then cut according to your recipe (slice, chop or dice).
In a large soup pot over medium heat, saute the leeks, onions, and butter until tender. Stir in potatoes, vegetable or chicken broth, and salt. Increase heat and bring just to a boil. Reduce heat to low, cover, and simmer for 35 to 40 minutes or until potatoes are tender. Remove from heat and let cool 10 to 15 minutes.
In a food processor or blender, puree cooled mixture until smooth. The soup can be made 1 to 2 days in advance up until this stage. Refrigerate until ready to finish.
When ready to serve, return mixture to soup pot. Stir in milk and cream; cook over low heat, another 10 minutes. Season to taste with salt. NOTE: Thin to desired consistency with the milk. Remove from heat and serve in soup bowls; garnish with chives.
This soup can be served either hot or cold.
Makes 6 to 8 servings.
* Learn how easy it is to make your own homemade Chicken Stock - Basic Chicken Stock.
Classic Vichyssoise Soup Recipe and History https://whatscookingamerica.net/Soup/VichyssoiseSoup.htm