Called vichyssoise in France, story has it that it was Julia Child who brought leek and potato soup to the attention of the United States when she published a recipe in her book Mastering the Art of French Cooking. She called it an American invention but that’s really debatable.
Pureed leek and potato soup had been popular in France since the 19th century. It is often called “Potage à la Parmentier” after the man who popularized potatoes in French cooking. The traditional ingredients for vichyssoise are leeks, potatoes, chicken stock and cream. The difference between French vichyssoise and Julia Child’s vichyssoiseis the absence of cream in the latter.
With all due respect to the French, I have to side with Julia Child with regard to the omission of cream in making leek and potato soup. I feel that cream, especially when used in copiuos amounts, drowns out the natural flavors of the leeks and potatoes.
Using butter — real butter — is crucial. None of those low-fat low-sodium substitutes. As for the leeks, it is a good practice to split them vertically to expose the layers before rinsing under the tap. That’s to make sure that any trapped soil will get washed away.
Choose a variety of potato that is waxy rather than floury. If the potatoes have thin skin, there is no need to peel them. Just cut into small pieces so that they cook faster and evenly. It also makes pureeing easier.
If your broth is unsalted or undersalted, or totally unseasoned, you’ll have to taste the soup at various stages of cooking, and add salt and pepper, as needed.
Full recipe below
Leek and Potato Soup
- In a thick-bottomed pan, melt the butter and add the sliced leeks.
- Cook the leeks, stirring occasionally, until very soft.
- Add the potato cubes to the leeks, sprinkle in salt and pepper, and stir to coat the potato cubes with butter.
- Pour in the broth, bring to the boil, lower the heat and cook until the potato cubes break apart when pierced with a fork.
- Off the heat, plunge an immersion blender into the pot and process until all solids are pureed.
- If the soup is too thick at this point, put back on the stove and pour in more broth. Bring to a simmer then add more salt and pepper, as needed.
- Ladle the leek and potato soup into bowls and garnish with fried shallots and chopped parsley.