1. Sauté onion in butter in a large skillet until tender. Add next 8 ingredients. Cover, reduce heat, and simmer 20 minutes or until carrots are tender.
2. Place half of mixture into the container of an electric blender or food processor fitted with the metal blade; process until smooth.
3. Pour into a bowl or pitcher; repeat with the remaining mixture. Stir in sherry. Cover and chill. Garnish soup with carrot strips, if desired.