Ingredients

• 2 tablespoons (1/4 stick) butter
• 2 cups thinly sliced leeks (white and pale green parts only; about 3 medium)
• 1 7- to 8-ounce white-skinned potato, peeled, diced
• 3 cups (or more) low-salt chicken broth
• 2 cups (packed) coarsely chopped watercress with some of stems plus small sprigs (for garnish)
• 1 cup (packed) baby spinach leaves
• 1 1/2 teaspoons fresh lemon juice
• 2 hard-boiled eggs, peeled, chopped (for garnish)

Instructions

1. Melt butter in heavy large saucepan over medium heat. Add leeks and potato; sauté until leeks are slightly softened but not brown, stirring often, about 5 minutes. Add 3 cups broth; bring to boil. Reduce heat, cover, and simmer until vegetables are very tender, 10 to 12 minutes. Add watercress and spinach; stir until wilted, about 1 minute. Cool slightly.
2. Working with 1 cup at a time, puree soup in blender until smooth. Transfer soup to large bowl. Stir in lemon juice; season with salt and pepper. Chill until cold, about 2 hours. Thin with more broth, if desired.
3. Ladle soup into bowls. Garnish center of each with hard-boiled eggs and small watercress sprigs.