Watercress is something that I usually pass by in the market, but more and more I've found that it's something that I really enjoy. As a part of the mustard family, it has much more flavor than many greens and nutritionally beats the pants off of lettuce.
But what else can you do with watercress aside from incorporating it into a salad and dressing it with a simple vinaigrette? The French have been using watercress to make a vibrantly colored soup called potage au cresson, or Watercress Soup, for hundreds of years.
This version from The Best Soups in the World by Clifford A. Wright is a simple and very flavorful take on the French classic. The soup gains texture from puréed potato and creaminess from the addition of a bit of cream and egg yolks. The peppery watercress makes for a soup that is not only beautiful to behold but peppery and fresh tasting.
- 1 medium-size all-purpose potato
- 2 tablespoons unsalted butter
- 1 small onion, finely chopped
- 2 bunches watercress (about 1 pound), leaves only
- 4 cups vegetable or chicken broth
- 1/2 cup heavy cream
- 2 large egg yolks
- Salt and freshly ground black pepper
Place the potato in a pot and cover with water by several inches. Turn the heat to medium-high and once the water comes to a boil, after about 15 minutes, reduce the heat to medium and cook until easily pierced by a skewer, about another 20 minutes. Drain, peel, and set aside.
In a flame-proof casserole or pot, melt the butter over low heat, then add the onion and cook, stirring, until it is translucent, about 10 minutes. Add the watercress and cook, stirring, until it has wilted. Add the broth and cook for 10 minutes. Transfer to a blender with the crumbled potato and purée for 3 minutes. (Don't worry, the potato will not become gummy as it would if you processed it alone.)
Blend the cream and egg yolks in the pot or casserole and then add the soup. Cook over low heat, seasoning with salt and pepper, until hot, about 10 minutes, without ever letting it come to an even near boil. Serve hot.