Heat oil in 4-quart saucepan over medium heat. Cook onion and ginger until onion is wilted, about 10 minutes, stirring occasionally. Add carrots, chicken broth, TABASCO® Green Sauce and salt. Heat to boil over high heat. Reduce heat to low; cover and simmer 20 minutes or until carrots are tender, stirring occasionally.
Cool soup slightly. In a blender or food processor, purée soup in small batches until blended. Cover and refrigerate soup until chilled, at least 2 hours.
Garnish soup with a dollop of sour cream, if desired.
Makes 5 cups.