The Real Leek and Potato Soup

Have you ever heard of liquid memory?  In France, it goes under the name “Leek and Potato Soup,” for no other dish is so emblematic of security, safety, deliciousness.  It’s more than a dish, it’s a touchstone of caring. 

No Soup is the Same

Every cook in France makes this soup because leeks and potatoes are simple, standard ingredients for much of the year.  Depending on the cook it may include more potatoes than leeks, more leeks than potatoes, water as a base, or chicken stock to make it rich.  Some top it up with cream, others use milk, some drizzle it with olive oil.  Herbs like thyme or bay leaf, a branch of rosemary, might jump in too.  

Cures Dinnertime Panic

This simple soup is as beloved in France as it is a solution to the panic of what to make for dinner. And it’s a soup that can be humble or fancy: I cannot count the number of times I’ve received an impromptu lunch or dinner invitation from October through April (high leek season) when the meal has included leek and potato soup, in all of its versions

The Leek is the Real Star

In France this soup isn’t called leek “and potato” soup. It’s simply Potage aux Poireaux, Leek Soup.  For the potato is a supporting actor, used to thicken.  In Normandy, potage aux poireaux includes crème fraîche too because, without it, the Norman meal is nothing.  In the south it might get the drizzle of olive oil, and elsewhere, the herbs.

Simple and Voluptuous

For me, the best version is the simplest, focused on the voluptuous leek. Right now, the leek is still gorgeous, firm, vibrant, juicy, and delicious.  Evenings are cool, too, so comfort in the guise of this soup is so very welcome.  It goes together in moments, then I like to serve it with a big bowl of crème fraîche on the side, so everyone dollop into their bowl just what they want. 

So jump in, take advantage of the leek and the potato now, both perfect actors in this shoulder season.For a more refined version use just the white parts of the leek; for more robust flavor, use at least 3-inches of the green, making sure to peel off the outer, tough leaves.

The “Recipe”

  • Take about 2 pounds (1 kg) of leeks, and trim and clean them well, by slitting them down their length and running them under cool water. The leek is grown in soil or sand, so they can be quite “soily”.
  • Peel a starchy potato – small, for more liquid soup; large for thicker soup. Cut it in cubes.
  • Melt a chunk of butter in a stockpot and add the leeks and the potato. Cook, stirring frequently, until the leek softens, about 8 minutes. Season with salt and pepper, stir, and add about 2 quarts; 2 liters of water – starting with 5 cups, 1.25 liters.
  • Cook the vegetables, covered, until they are very soft all the way through. Puree the soup (a wand blender is great here). If you’d like the soup thinner, add water a bit at a time. If you’d like it thicker…well, either you cook another potato and add it, or you decide you don’t want it thicker. 
  • Season it to taste. Either stir in crème fraîche (or heavy cream), or serve it alongside the soup, which you can also season with a dusting of freshly grated nutmeg.
  • If you have leftover soup, you can serve it chilled and call it Vichyssoise!

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