In this recipe, leeks are used in place of onions to give a more delicate and sweet flavour. This soup is packed with Vitamin K, a prominent nutrient in both leeks and watercress which supports healthy bones, brain tissue repair and growth. The liquid base, chicken bone broth, is one of the most healing foods. It contains gelatin and glycine which protect the gut lining, skin and digestive tract.
2 tbsp (1/4 stick) butter
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.
Chill until cold, about 2 hours. Thin with more broth, if desired.
Ladle soup into bowls. Garnish center of each with hard-boiled eggs and small watercress sprigs.