Simmer vegetables and fruits in broth in a 3-quart heavy saucepan, covered, until very tender, about 12 minutes. Stir in cream, butter, curry powder, and salt and heat just until hot (do not boil).
Purée soup in a blender until smooth (use caution when blending hot liquids). Thin soup with water if desired and serve sprinkled with chives.
Cooks' Note
Soup can be made 2 days ahead and chilled, covered.