MIX first 3 ingredients in medium bowl until blended. Gradually stir in broth.
COOK and stir celery, onions and peppers in 2 Tbsp. hot oil in large skillet on medium-high heat 5 min. or until crisp-tender. Remove from skillet; cover to keep warm. Heat remaining oil in same skillet. Add chicken; cook and stir 8 to 10 min. or until done. Stir in broth mixture; cook and stir 3 min. or until mixture boils and thickens, stirring occasionally.
ADD vegetables and nuts; mix well. Serve over rice.