Few things are more refreshing, more nourishing and more pleasing to the eye on a hot summer day than a chilled soup with a bright green color. A favorite of mine in the summertime is a chilled potato and watercress soup.
Potato Watercress Soup is of course a variation of Vichyssoise, the chilled potato leek soup whose origin may be French or American but which probably belongs to the vanished world of “continental cuisine.”
The technique for making a bright green soup is the same, no matter what ingredients provide the chlorophyll: You cook your soup base, and when it is almost done, you add the green ingredient at the last minute, cook just until it’s wilted, blend it right away, then transfer the blended soup to an ice bath.
A trick I learned in France is to stir the chilling soup with a whisk: whisking the soup aids in convection and makes the soup chill down in half the time.
If you don’t have watercress, you can substitute spinach, arugula, or a big handful of green herbs.
Potato Watercress Soup
Serves 4-6.
Ingredients
3 tablespoons butter
3 leeks , white part only, diced and washed
¼ cup white wine
3 large Yukon Gold potatoes, cut into small dice
2 cups chicken broth
1 bunch watercress
4 tablespoons sour cream
Salt and freshly ground pepper
Few shavings fresh nutmeg
Few shots hot sauce
Coarse breadcrumbs for garnish
Directions
In a heavy bottomed pot over medium heat, add the butter and a roughly equal amount of water. Bring to a simmer and add the leeks and a pinch of salt. Cover the pot and cook until the leeks are tender, about 12- 15 minutes. Add the white wine and reduce by half.
Add the potatoes and chicken broth, and add a little bit of water just to cover and another pinch of salt. Bring to a simmer and cook the soup until very tender, about 40 minutes. Add the watercress and cook until wilted, about 2 minutes.
Place a clean container inside an ice bath. Immediately transfer soup mixture to a blender and blend well, adding the sour cream, nutmeg and hot sauce and a little salt and pepper. You may need to blend the soup in batches. Quickly transfer the blended soup to the clean container set and ice and place a whisk inside the blended soup, whisking often until chilled. Serve when cold, garnished with breadcrumbs.
