In A Small Bowl, Combine The Flour, Salt And Pepper. Set Aside 4-1/2 Teaspoons For Sauce. Sprinkle The Remaining Flour Mixture Over Both Sides Of Chicken. In A Large Nonstick Skillet Coated With Nonstick Cooking Spray, Cook Chicken In Oil Over Medium Heat For 7-9 Minutes On Each Side Or Until Juices Run Clear. Remove And Keep Warm. In The Same Pan, Saute Onion In Butter Until Tender. Add Thyme And Reserved Flour Mixture; Stir Until Blended. Gradually Stir In The Broth And Lemon Juice, Scraping Up Any Browned Bits From Bottom Of Pan. Bring To A Boil; Cook And Stir For 2 Minutes Or Until Thickened. Serve Over Chicken. Sprinkle With Parsley.