Add the carrots, sweet potatoes, chicken broth and salt and bring to a boil. Cover and simmer over low heat until vegetables are very tender, about 25 minutes. Stir in the apples and honey. Using a stick blender, puree the soup until smooth and creamy. (Alternatively, cool the soup slightly, then puree in a blender in batches. Be sure to leave the hole in the lid open, and cover with a kitchen towel, to allow the steam to escape.)