- 1 large buch watercress (about 6 ounces)
- 1/4 cup (1/2 stick) butter
- 1 onion, chopped
- 2 large parsley sprigs
- 2 large thyme sprigs
- 1 large garlic clove
- 1 bay leaf
- 2 cups canned low-salt chicken broth
- 1 pound russet potatoes, peeled, cut into 1/2 inch pieces.
- 1 cup (or more) milk
- Coarsely chop watercress leaves and stems seperately. Melt butter in heavy large saucepan over medium-low heat. Mix in onion, parsley sprigs, thyme sprigs, garlic, bay leaf, and watercress stems. Cover; cook until onion is tender, stirring occasionally; about 12 minutes. Add broth and potatoes; bring to boil. Reduce heat cover and simmer until potatoes are very tender, about 25 minutes.
- Discard parsley, thyme, and bay leaf. Purée soup in processor until smooth. Return soup to same saucepan. Add 1 cup milk and watercress leaves; bring to simmer, adding more milk if soup is too thick. Season with salt and pepper. Transfer to bowl. Chill until cold, about 4 hours.