Heat 2 teaspoons oil in nonstick skillet over medium heat. Brown chicken on both sides. Remove chicken. Add remaining oil, mushrooms, onion and garlic; saute until tender. Add tomatoes, 1/2 cup broth, thyme, salt, pepper and lemon zest. Return chicken to skillet. Cover; simmer 10 to 12 minutes until chicken is cooked. Whisk together flour and remaining broth. Remove chicken; keep warm. Stir flour mixture into skillet; cook, stirring constantly, until mixture thickens and boils. Remove zest. Sprinkle with parsley. Serve chicken and sauce over pasta if you wish. CHICK 19