Known as caldo verde in Portugal, this hearty soup traditionally is made with linguiça or chouriço, but just about any type of smoked, spiced sausage, including kielbasa or Cajun andouille, yields a flavorful potful. Often, water is used as the base for the soup, though chicken broth, which we call for here, deepens the flavor. Some versions are brothy, with the potatoes left in chunks, while others are pureed and thick. We chose to puree, including some of the sausage, which yields a rich, well-seasoned soup. Then the kale is added at the end and cooked briefly so it offers textural contrast and vibrant color.