In 5-quart Dutch oven, heat oil over medium-high heat. Add onion, bell peppers and jalapeño chile; cook 3 to 4 minutes, stirring frequently, until vegetables are just crisp-tender. Add flour and taco seasoning mix. Cook 1 minute, stirring constantly. Stir in tomatoes and green chiles. Heat to simmering. Remove from heat; stir in chicken, 1 cup of the cheese and 1 cup of the sour cream.