Vichyssoise: cold potato leek soup

My dad always sad that hot soup is the best thing on a hot day.  That may be true.  But cold soup is damn good, too.  Vichyssoise is puréed leek and potato soup, served chilled, and it is pretty much ideal for a hot summer night.

I’d always assumed that vichyssoise was French.  Its name is French (it literally means, “from Vichy”- a town in France) and my French mother cooked it.  Today I learned that vichyssoise was in fact first cooked by Chef Louis Diat at the New York City Ritz Carleton in 1917.  Puréed leek and potato soup had been around in France for generations (centuries, probably), but Diat was the first to serve it chilled and with cream.  Well done, sir.  Even if the soup was developed in the US, it is still French in its simplicity and subtlety.  There are very few ingredients, but put together, they are exceptionally delicious.

4-5 leeks, prepared (see below) 
3 large russet potatoes, peeled and sliced into thin rounds
1 medium onion, chopped
4 c. stock (I used veggie stock)
butter
1/2 c. milk
1 c. cream
salt (white pepper, optional)
chives, olive oil and lemon, for garnish

The first step is to prepare the leeks.  The problem is that leeks are filthy, sandy vegetables- probably the filthiest and sandiest there is.  You need to wash your leeks several times to ensure that there aren’t stray sand particles hiding between the the leek layers.

Here is my technique:

1. Rinse the sand off the outside of the leeks.
2. Remove the tough green stalks and the bottom root ends of the leeks.  You should be left with the white and very light green stem.
3. Rinse the leeks again.  Also, rinse your cutting board and your knife, because these are probably sandy, too, and if you don’t rinse these you’ll just be transferring sand to your clean leeks.
4. Slice each leek in half longways.  This allows you to peel back the individual layers of the leek.   Trust me, there is sand in between the layers.  Peel back each layer under cool running water.
5. When you’ve rinsed all the leek halves thoroughly, rinse off your knife and cutting board again.
6. Cut-side down, chop the leek halves into 1/4 inch slices.  Now you have hundreds of tiny C-shaped pieces of leek.  Put the slices in a colander and- you guessed it- rinse them under cool running water.

I know, this process is excruciatingly tedious.  However, going through the trouble of cleaning the leeks is way better than ruining an entire dinner with sand in your soup.

Now, to the actual preparation of the vichyssoise.  Get the biggest soup pot you have. In it, melt a large chunk (I’m tempted to say “a healthy chunk”) of butter on low heat.   Add the chopped onions and leek slivers.  Let these cook gently for at least 20 minutes: they should get translucent, but not brown.  If they are turning brown, reduce the heat.  You will be shocked and appalled by how much the veggies cook down (I’d say they cook down by 3/4).  Stir the veggies every few minutes.

While the onions and leeks are cooking, peel and slice the potatoes.  The thinner you slice the potatoes, the less time you will spend boiling them in the soup.  If it’s an especially hot day, you might want to take that into consideration.  I set the potato slices into a big bowl of cold water while I wait for the leek-onion mixture to finish.  This prevents discoloration and removes some of the excess starch from the potatoes.

Add the potatoes to the leeks and onions.  Stir.  Add stock and salt to taste.  Stir and bring to simmer. Cover and cook for at least 20 minutes, or until the potatoes are easily smashable.  

Purée the soup. If you have an immersion blender, this is the time to use it.  Otherwise, let the soup chill a bit and ladle the soup into a blender.  Either way, blend the soup until it is even and smooth.  Blend in 1/2 c. of cold milk.  Chill the soup in the refrigerator until ready to serve.

Before serving, stir in cold cream.  Garnish each bowl with chopped chives and maybe a splash of olive oil.  Serve with a lemon wedge.