This speedy but filling soup has a mildly spiced flavor, thanks to a cup of tomato salsa in the mix. It reheats nicely too, so you might want to double the batch and freeze what's left for another night.
Heat the salsa in a large saucepan over medium heat, stirring often, for about 5 minutes. Stir in the beans and broth. Bring the mixture to a boil, then lower the heat and simmer the soup, covered, for 15 minutes.
Let the soup cool slightly, then ladle half of it into a food processor or blender and puree it. Return the pureed soup to the pot. Stir in the lime juice and chopped cilantro and heat the mixture through. Serve the soup warm, topped with a dollop of sour cream, if desired. Makes 4 servings.