1. Melt butter with oil in a Dutch oven over medium heat; add bell pepper and next 3 ingredients, and sauté 8 to 10 minutes or until tender.
2. Stir in chicken broth and next 4 ingredients. Bring to a boil; cover, reduce heat to low, and simmer 25 to 30 minutes. Let cool 20 minutes.
3. Process soup, in batches, in a food processor until smooth, stopping to scrape down sides. Return to Dutch oven, and keep warm until ready to serve. Garnish, if desired.
Note: To make ahead, let soup cool, and store in an airtight container in refrigerator up to 2 days. Reheat in a saucepan over medium-low heat, stirring often.
Note: Nutritional analysis does not include garnishes.