Chef Louis Diat of New York City's original Ritz-Carlton Hotel once prepared eight portions of his famous soup to be delivered to the Manhattan town house of Sara Delano Roosevelt, Franklin D.'s mother, at her request—and enclosed this recipe.
This chilled summertime soup is smooth and sumptuous.
Yield: serves 8
4 tbsp. butter
4 leeks, white and light green parts only, thinly sliced
1 medium onion, thinly sliced
5 medium white boiling potatoes (about 2 1⁄4 pounds), peeled and thinly sliced
2 cups milk
2 cups light cream
1 cup heavy cream
2 tbsp. finely chopped chives
Heat butter in a large pot over medium-low heat. Add leeks and onions and cook, stirring occasionally, until soft but not browned, about 20 minutes. Add potatoes, 4 cups water, and salt to taste and increase heat to high. Bring to a boil, reduce heat to medium-low, and simmer, stirring occasionally, until potatoes are soft, 50–60 minutes.
Strain soup through a mesh sieve into a bowl, pressing and scraping the solids with a spoon. Clean pot and return soup to it. Whisk in milk and light cream, bring to a boil over high heat, then remove from heat and let cool. Strain soup through a fine-mesh sieve (finer than the first), pressing and scraping it into a bowl with the spoon, leaving behind a thick paste of solids. Discard solids. Stir heavy cream into soup, cover with plastic wrap, and refrigerate until chilled. Season soup with salt to taste.
Divide soup between 8 soup bowls and garnish with chives. Serve cold.