COOK chops in large nonstick skillet on medium heat 4 min. on each side or until done (160ºF). Transfer to platter; cover to keep warm.
ADD onions and mushrooms to skillet; cook 6 min. or until onions are crisp-tender, stirring occasionally. Stir in sour cream and broth; cook until heated through, stirring frequently. (Do not boil.)
SPOON sauce over chops; sprinkle with parsley.