GINGER AND SWEET POTATO SOUP WITH CILANTRO

Steps:

• Heat oil in a 4- to 6-quart Dutch oven or soup pot over medium-high heat. Add leek and carrot; cook, stirring often, until they begin to soften, 2 to 3 minutes. Stir in sweet potatoes (or yams) and chopped ginger. Add broth and bring to a boil. Cover, reduce heat to low and simmer until sweet potatoes are soft, about 30 minutes.
• In batches, if necessary, transfer the soup to a blender or food processor and process until smooth. Return the soup to the pot, season with salt and reheat. Just before serving, stir in grated ginger. Whisk yogurt and milk in a small bowl until smooth. Ladle soup into bowls; drop a large dollop (or several small dollops) of thinned yogurt onto each one. Draw the tip of a knife or a toothpick through the yogurt to make decorative swirls. Garnish with cilantro and serve with lime wedges for squeezing into the soup.