This soup is easy to make, delicious to eat either hot or chilled, and it’s a soup that, once tasted, you will want to make again and again. It is made with two super... greens, watercress and arugula, and you get a protein assist from frozen peas — a pantry staple we all love. The resulting soup has a color that is out of this world, the texture of light cream, and a peppery taste that is mellowed by the sweetness of Vidalia onion and peas. As the ingredients are few, it’s a good idea to use a good quality chicken broth or light vegetable broth if you are vegetarian or vegan. Either way, it is a keeper.
Take the watercress and separate the thick, tough stems from the leaves. Reserve the leaves and finely dice the stems.
Over a medium high flame, heat the oil in a five quart Dutch oven or other heavy pot. Add the diced watercress stems and the Vidalia onion. Reduce the heat to medium, sprinkle with salt, and sautée until the watercress stems and onion have softened but not taken on any dark color, about five minutes.
Add the stock and bring to a boil over medium-high heat. When the soup boils, reduce heat to medium-low and simmer for 15 minutes.
Add the frozen peas. Cook two minutes or until just soft. Add the reserved watercress leaves and the arugula, stirring until they start to wilt and turn a vivid bright green. Turn off the heat.
Blend the soup with an immersion blender or in batches using a high-speed blender (for safety, fill the vase ½ full each time). Return blended soup to the pan and adjust seasoning as needed. Warm through if serving hot or chill in the refrigerator until cold. Serve with a dollop of yogurt, chopped chives, and croutons, if using.
If experiencing diarrhea, make sure to cook the vegetables well and blend to a smooth puree. Omit the chives and croutons when serving.
Peas should be added still frozen. If you use fresh peas, blanch them in salted boiling water for about 5 minutes or until just tender before adding the greens to the pot.
If you can find the peppery wild Italian arugula, it’s an added plus.
You can also substitute ghee or butter for the olive oil.
If you make this with vegetable stock or broth, make sure it is light in texture and taste.