Reduce heat to medium; add remaining 1 tablespoon oil to skillet. Add onion; cook 8 to 10 minutes, stirring occasionally, until browned and softened. Add flour; cook and stir 1 minute. Stir in broth and orange zest; heat to boiling. Add pork chops back to skillet; spoon sauce over top of pork. Reduce heat to low; cover and simmer 5 to 7 minutes or until pork is cooked through (at least 145°F). Transfer pork chops to serving plate.