Vichyssoise is a good example of how cooking evolves.  A French chef, Louis Diat, working at the Ritz-Carlton Hotel in New York, was looking for a cold soup for the menu around 1920.  He remembered his mother’s potato and leek soup (potage Parmentier), and transformed it by adding cream, chilling it,  serving it with chives, and calling it Vichyssoise.

This version is adapted from The Cooking of Provincial France in the excellent Time-Life Foods of the World books published in the 1960s.  This will make about 1.5 quarts of soup and takes about an hour plus chilling time.  (I made a relatively small batch since I had only 1 russet potato to work with.  It can easily be scaled up.)

1 large Russet potato (about 333 g.), peeled and diced (about 2 cups)

The white part of 2 leeks (about 145 g.), sliced and rinsed (about 2 cups)

1 qt. chicken broth

¾ cup heavy cream

½ tsp. salt

½ tsp. freshly ground black pepper

Sliced chives or green onions for garnish

Put the potato and leeks in a large saucepan with the chicken broth.  Bring to a boil and reduce to a simmer.  Cook partially covered for 40-50 minutes until the potatoes and leeks are soft.

With a slotted spoon, put the potato and leek solids into the bowl of a food processor and briefly pulse until the mixture has a texture like apple sauce.  Add to the bowl of the food processor the chicken broth the potatoes and leeks were cooked in, cream, salt and pepper, and pulse briefly to mix.  Check seasoning.  Chill well before serving with a garnish of chives (traditional) or green onions.  Recheck seasoning when well chilled since it may want some more salt.