In a large saucepan, heat oil over medium-high heat; saute carrot, celery and onion until tender. Add garlic; cook and stir 1 minute. Stir in rice, seasonings and broth; bring to a boil. Reduce heat; simmer, covered, until rice is tender, about 15 minutes., Mix flour and milk until smooth; stir into soup. Bring to a boil; cook and stir until thickened, about 2 minutes. Stir in chicken; heat through.