Sorrel Soup

Directions

1. 1
   {"0":"Stack the sorrel leaves and cut into ribbons. Set aside. In a large, heavy saucepan with a tight-fitting lid, heat the butter over medium heat. When the butter has melted, add the onion. Cook, stirring occasionally, until the onion is well-browned, about 20 minutes. Add the sorrel, potatoes and broth. If the broth does not cover the contents, add a little water. Bring to a boil, reduce heat to low, cover and cook until potatoes are tender, about 15 minutes. When the potatoes are done, transfer half of the mixture to a blender or food processor (blenders give smoother results). Process carefully until the mixture is pureed and smooth. Repeat with remaining soup. Return the soup to the saucepan over low heat. Temper the egg by whisking it with about one-quarter cup of soup, then pour the egg mixture into the pan. Cook, whisking constantly, until the soup thickens, about 5 minutes. Do not boil.","2":"If serving hot, garnish each portion with sour cream or yogurt. If serving cold, cover the soup tightly and refrigerate for at least 4 hours before serving. Garnish with sour cream or yogurt and chopped cucumber and radish."}