- 1 1/4 pounds russet potatoes, peeled, cut in 1-inch pieces
- 1 1/2 cups sliced green onion (2 to 3 bunches)
- 2 tablespoons butter
- 6 cups reduced-sodium chicken broth
- 6 cups watercress, tough stems removed (3 bunches), or baby spinach leaves
- 3 tablespoons snipped tarragon
- 1/2 cup dry white wine or reduced-sodium chicken broth
- Ground black pepper
- 1/2 cup sour cream (optional)
- In Dutch oven cook potatoes and onion in hot butter over medium heat for 3 to 5 minutes, stirring occasionally.
- Add broth and simmer, covered, for 20 minutes.
- Stir in watercress.
- Return broth to simmering.
- Simmer, covered, for 3 to 5 minutes, until greens are tender.
- Remove soup from heat.
- Cool 15 minutes.
- Stir in tarragon.
- Puree soup using immersion blender or in batches using a blender.
- Stir wine into soup.
- Season with salt and pepper.
- Heat through over low heat.
- Top each serving with sour cream.