The problem is, I can't find a single citation before the 1930s.
"Vichyssoise" was certainly popularized by the "This New York" column by Lucius Beebe in the New York Herald Tribune.
15 June 1929, The Restaurateur and American Hotelier, pg. 9:
Ritz-Carlton Hotel Chef
Explains Popularity of
(Louis Diat explains everything EXCEPT vichyssoise! - ed.)
15 June 1935, New York Herald Tribune, "This New York" by Lucius Beebe, pg. 12, col. 1:
During the torrid months of last season, we never could mention Creme Vichysoise as having been on a menu without receiving at least one request for the formula for this superlative summer soup. We, therefore, have obtained his own private recipe from Paul Moreau, chef de cuisine at the Madison, and your own cook may paste it up between the butcher's calendar and the foie-gras firkin once and for all. It is:
"Peel and wash thoroughly a pound and a half of young red carrots.Slice very fine and simmer in a little fresh butter for about ten minutes.Add two tablespoons of flour and mix well. Add a quart of chicken broth and cook slowly for forty-five minutes after seasoning with salt and a dash of paprika. Strain twice through a fine sieve to get a smooth-textured cream.
"Prepare in a flat pan a half pint (col. 2--ed.) of cream and three egg yolks; stir well together and mix slowly with the cream of carrots. Put onthe stove again and keep stirring to the boiling point. Remove immediately from the fire and strain again through cheese-cloth. Place in a cool place and serve very cold, preferably in a bowl surrounded with ice."
6 July 1935, New York Herald Tribune, "This New York" by Lucius Beebe, pg. 10, col. 1:
It is not the purpose of turning this department into a supplement ofFannie Farmer's "Boston Cook Book" that prompts it to run recipes for creme vichyssoise, and this will be the last of them. Scott Wilson, the industrial designer, however, took exception to the one chronicled here a few weeks since and sends one (col. 2 - ed.) ravished from the private files of Fred Beaumont, chief steward of the Central Park Casino. It is, he says, a more positive and masculine summer soup than our other.
Take four bunches of leeks, using the white part only, and be sure to wash them very well to avoid any sand. Mince very fine and put in a casserole with one-quarter of a pound of fresh sweet butter, cook for ten minutes ona very slow fire to prevent coloring. peel four medium-sized potatoes, slice them very thin and add to the leeks. Add one quart of brothand a stalk of celery and some parsley attached together, boil the whole for thirty minutes. Take this soup through a very fine strainer and add one pint of heavy cream, salt, ground nutmeg, some finely chopped chives and three or four drops of Worcestershire sauce and stir well. Chill in a china bowl andbe sure not to use any metal container, as this would alter the taste. Serve very cold.
To the Queen's Taste
by Helen Train Hiiles
New York: Random House
Pg. 39: Vichyssoise, Soup
1 March 1937, New York Times, pg. 21:
...the Gourmet Society, who had gathered at the Meadowbrook Restaurant, 62 East Fifty-fifth Street.
Yesterday's menu included vichysoisse, a cold soup for which the Meadowbrook is noted;
13 February 1938, Washington Post, "Cooking For One" by Theodore Hall, pg. B10:
I DIDN'T SEE any vichyssoise soup or zabione in "For Men Only,"
20 March 1938, Chicago Daily Tribune, George Rector column, pg. E2:
Within the last few years a new soup had made its appearance. It's a wealthy soup and is served only in the fashionable hotels and restaurants. The name of this soup is Vichyssoise and is served cold.
Cut en Julienne, which means in very fine strips about two inches long, the white part of four leeks. Also slice thinly one small onion. Melt one or two tablespoons of butter in a saucepan and brown lightly the leeks and onion, then add five medium sized raw potatoes, thinly sliced, along with one quart of light colored stock. Chicken or veal stock will do. Season with one=half teaspoon salt and a light pinch of cayenne pepper. Simmer gently, with cover on, for about one-half hour. Strain the soup through a fine strainer and force through the strainer as much of the vegetable pulp as you can. To this add two cups of hot milk and two cups of hot cream and bring just to a boil.
Let the soup cool and add another cup of cream. Place in refrigerator until thoroughly chilled. Just before serving sprinkly over the top of each cup one-half teaspoon of finely chopped chives. You will quickly observe that this Vichyssoise is a very rich soup, even without that last cup of cream.
16 July 1938, New York Herald Tribune, "This New York" by Lucius Beebe, pg. 12, col. 1:
For the potage enthusiasts who are forever in search of a recipe for creme vichysoisse, this department herewith prints its annual formula, stemming this year from the kitchen of Jack and Charlie's ("21" Club--ed.), where this particular cold soup is really one of the things to have. Slice two onions, three leeks and six medium-size white potatoes; put onions and leeks in pan to brown and add sliced potatoes, two teaspoonfuls of flour and one gallon of white soup stock. Cook forty minutes or until potatoes are ready to fall apart, strain, cool and add heavy cream to taste. Top off with nutmeg and salt and serve as cold as possible, preferably in a soup cup packed in ice. These proportions are for twelve persons.
12 August 1938, New York Herald Tribune, Clementine Paddleford column, pg. 9, col. 6:
Lucius Beebe, our Saturday neighbor on this page, mentioned creme vichysoisse one week in July and gave a recipe coming from a restaurant kitchen where this particular cold soup is really one of the things to have. Ever since, readers have been phoning the Home Institute to ask for a home-size recipe. We have made vichysoisse (slur the words together like vishee-swahzz) twice this week and now have the restaurant's recipe down to amounts for six helpings. It's a cold soup, as we said, made with leeks, or use green onions; there are chopped chives in it and sliced potatoes and stock of veal or chicken. It is whitened with cream and very delicate as to flavor, but hearty, too. Make it in the early morning and let it chill through the day for the evening meal. Scallops with anchovy crumbs will make the family shove closer to their plates. (...)
Where to Dine in Thirty-Nine
by Diana Ashley
New York: Crown Publishers
(Vichyssoise recipe by Louis Diat - ed.)
30 July 1939, Washington Post, "This New York" by Lucius Beebe, pg. A2:
Comes summer and this department is invariably deluged with requests for the formula of the cold carr-and-potato soup that has come to be known on the town's menus as creme vichysoisse. The recioes are endless, since the chef at the Colony sees not eye to eye with the kitchen overlord at Jack and Charlie's, and only civic ordinance prevents the maitre de cuisine at the Meadowbrook from engaging sabers at dawn in Central Park with Crosby Gaige. There are as many ways of building vichysoisse as mint juleps. The scholarly Bill Rhode, chronicler of royal gastronomy and himself an amateur chef ranking with Selmer Fougner and Theodore Codman, writes us, plaintively, however, on the genesis and derivation of the name itself.
"Much has been said and written recently," says Mr. Rhode, "on just what is that delectable cummer concoction called 'vichysoisse,' or 'vichyssoise,' or even 'vichy soisse.' Like seven cities claimed to be Homer's birthplace, so seem to be many cooks and restaurants in our fair city who lay claim to the honor of having created this No. 2 company of nectar and ambrosia, We all agree that it is a cold cream soup, having potatoes and leeks as its base. Some use baked potatoes, others boiled ones; some use cour cream, others prefer sweet. If this is agreeable to the various gourmets and gourmettes, of which there seems to be a considerable number, then vichy - I'd rather not go through the various forms of spelling again - it a very old Scotch soup known during the early part of the nineteenth century as 'cock-a-leekie.' As the name implies, it was made with a capon or any old rooster and leeks. Potatoes were used as thickening, and sometimes cream was added. Louis Bisler quotes the same soup as 'creme auz poireauz paysanne.' Emile Bernard, in his memoirs as chef to Emperor William I of Germany, calls it, very condescendingly, 'lauchsuppe.' New York's own Delmonico had it many times on its menu under the name 'puree de pommes de terre a la Benton.' The Ritz Koof used to serve it in the early -20s as 'cold cream of leeks,' and I must have had gallons of it during the summers of '26 and '27 at Roberts', who thought the soup most plebian and called it 'cold leek and potato soup.' Even Mmr. Sevigne reports it made with potatoes, leeks and watercress and calls it 'creme Akenoise.' But nary a word about vichy. . . . To tell the truth, the word vichy...is meant to express that the soup is made in the manner of vichy, or 'a la vichy,' then the term is chosen most incorrectly, as 'in the manner of vichy' always denotes, gastronomically speaking, a dish that has carrots as its bade. One old hotel in New York, as a matter of fact, carries a cream of carrot soup on its menu and calls it correctly 'creme vichyssoise.'"
23 September 1939, Appleton (WI) Post-Crescent, Dale Harrison's In Old New York, pg. 6, col. 3:
Some enthusiastic remarks here a while back about the epicurean delight provided by Vichyssoise have brought me quite a bit of mail, including a letter from a lady in Tennessee who says that if I would send her some green onions she will turn out a pot of Vichyssoise to shame anything I ever tasted. That's all right, but I don't have any green onions.
Another note on the subject came from the inventor of Vichyssoise, M. Louis Diat, head chef of the Ritz-Carlton, who sent me the recipe and an account of how this queen of cold soups was created.
Diat was born in Vichy, France, and his mother - like most French housewives - served her children plenty of hot potato soup. Years later as he sought to invent some new and startling cold soup for the Ritz-Carlton menu, he remembered that fine soup of his mother's. He also recalled that patty-cake rhyme, "some like it hot, come like it cold." Out of that combination of thoughts came Vichyssoise, named for his birth place.
I have no intention to bore you with the recipe, but it is interesting to note the great pains chefs take in making such a seemingly simple thing as a bowl of soup. After boiling a concoction of leeks, onions, butter and potatoes ahile in white consomme, he passes it through a fine muslin. To the resultant liquid he adds milk and cream and seasoning, cooking some more; and then he passes it through another fine muslin. Heavy cream is added following the second "screening," and the soup is ready to chill and serve. It sounds like a lot of work. Anyway, that's Vichyssoise.
A Book of Gastronomic Adventure, With the Menus of Great Meals and the Original Recipes of the Chefs Who Made Them
by G. Selmer Fougner (of the NY Sun - ed.)
New York: M. Barrows
Pg. 270: Creme Vichyssoise (Diat).
7 July 1946, Los Angeles Times, Clementine Paddleford column, pg. 17:
Louis Diat, executive chef of the Ritz Carlton Hotel, claims the honor of having introduced vichyssoise to America.
When Louis Diat was a boy in France one of his favorite soups was the leek and potato soup with a chicken stock base. In summer when the children wanted something cool, the ingenious Madam Diat merely added cold, creamy milk to their favorite potage. Twenty years later when the Ritz Carlton opened a roof garden and the great chef, Monsieur Diat, started searching his brain for hot-weather cooking ideas, his mother's soup came to mind.
He worked out the formula, then cast about for a name - some reminder of home. The little town he came from was almost unknown, but close by was Vichy, the famous watering place, so he called the soup vichyssoise glace.
30 August 1957, New York Times, pg. 19:
Louis Diat, Chef de Cuisine, Dies;
Creator of Vichyssoise Was 72
Artist of the Menu 41 Years
at Ritz-Carlton Raised Leek
and Potato to Greatness
Louis Diat, the great chef who created vichyssoise, died yesterday at New York Hospital. He was 72 years old.
M. Louis was known for numerous culinary creations that have become a traditional part of the bill of fare in fine restaurants, but he will probably be most widely remembered for what he did with the lowly leek and humble potato: creme vichssoise glacee, a light and subtly tart soup he introduced at the Rizt-Carlton in 1917, seven years after the hotel opened.
The hotel took special pride in its summer roof-garden restaurant, and M. Louis worked hard at dishes to tempt appetites stunned by New York summers. He remembered the leek and potato soup his mother made in France and how he and his brother Lucien - now the chef at the Hotel Plaza-Athenee in Paris - woulod take leftover soup and add chilled milk to it.
Experiment in Kitchen
Experimenting in his New York kitchen, M. Louis came up with his modern version. The recipe had been modified by other cooks but M. Louis always insisted in making it the way he did when it became an immediate success:
CREME VICHYSSOISE GLACEE
4 leeks, white part
1 medium onion
2 ounces sweet butter
5 medium potatoes
1 quart water or chicken broth
1 tablespoon salt
2 cups milk
2 cups medium cream
1 cup heavy cream
Finely slice the white part of the leeks and the onion, and brown very slightly in the sweet butter, then add the potatoes, also sliced finely. Add water or broth and salt. Boil from 35 to 40 minutes. Crush and rub through a fine strainer. Return to fire and add 2 cups of milk and 2 cups of medium cream. Season to taste and bring to a boilo. Cool and then rub through a very fine strainer. When soup is cold, add the heavy cream. Chill thoroughly before serving. Finely chopped chives may be added when serving.
Named for French Spa
M. Louis named it "Vichyssoise" after Vichy, then known simply as a watering spot where Frenchmen rested their livers, but also known for fine cooking for patients tired of resting the organ to which most French ills are ascribed.
The chef had strong feelings about names for dishes. He thought it proper that they should keep the ones given them by their originators - even if it made menus a bit difficult for those not familiar with French.
But M. Louis was not unbending. When it was ointed out during the depression that people might be more willing to spend money on French cuisine if they could read the menus, he agreed to a compromise, and henceforth his materpiece appeared on Ritz-Carlton menus as "Cream Vichyssoise Glacee."