In the first volume of her opus, Mastering the Art of French Cooking, Julia Child writes that “leek and potato soup smells good, tastes good, and is simplicity itself to make. It is also versatile as a soup base; add watercress and you have a watercress soup, or stir in cream and chill it for a vichyssoise. To change the formula a bit, add a cup or two of carrots, string beans, cauliflower, broccoli, or anything else you think would go with it, and vary the proportions as you wish … Many of the delicious soups you eat in French homes and little restaurants are made just this way, with a leek and potato soup base to which left- over vegetables or sauces and a few fresh items are added…You may find you have invented a marvelous concoction, which you can keep as a secret of the house.”
That may be exactly how vichyssoise, arguably America’s most famous twentieth century soup, was first created. Some suggest that French King Louis XV (1710 to 1774) accidentally invented it due to his paranoid fear of being poisoned. He insisted that numerous servants taste his favorite potato soup before him, and when it finally arrived at his table it was cold. The King declared that he preferred cold potato soup.
A more likely, and widely accepted, history is that the soup was the brain child of Chef Louis Diat of New York’s Ritz Carleton Hotel. In the days before air conditioning, diners at the Ritz were served in a Japanese roof garden on sultry summer days, and Diat sought cooling recipes. In 1950, he told The New Yorker that “In the summer of 1917, when I had been at the Ritz seven years, I reflected upon the potato and leek soup of my childhood which my mother and grandmother used to make. I recalled how during the summer my older brother and I used to cool it off by pouring in cold milk and how delicious it was. I resolved to make something of the sort for the patrons of the Ritz.” The soup became so popular that Diat put it on the menu year round in 1923.
He named the soup after the famous French spa town of Vichy, near where he was born, but in 1941 a group of American chefs voted to rename it “crème gauloise” because they disapproved of the Vichy government’s collaboration with the Nazis. The new name didn’t stick.