Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   4                    Chicken breast halves, without skin
   2      teaspoons     Dijon mustard
   3 1/2  tablespoons   White wine vinegar
   2      teaspoons     Garlic -- minced
   2      teaspoons     Honey
   1 1/3  tablespoons   Fresh thyme -- or 2 teaspoons
                        Dried -- minced
     1/3  teaspoon      Coarse salt
   1 1/3  dashes        Red pepper flakes
   1      tablespoon    Olive oil
   4      sprigs        fresh thyme

Preparation:

Place the chicken breasts within a folded piece of plastic wrap; slightly flatten upper portion of each breast with the broad side of a chef's knife to promote even grilling. Place breasts in a shallow glass or ceramic dish. Place mustard, vinegar, garlic, honey, thyme, salt and pepper flakes in a small bowl; stir with fork to combine. Add oil a little at a time and whisk to combine marinade. Pour marinade over breasts. Cover with plastic wrap and marinate in refrigerator, turning once or twice in marinade, for at least 2 hours, or up to 4 hours. Remove breasts from marinade, scraping any bits clinging to chicken back into the shallow dish. Transfer all marinade to small saucepan and bring to a boil; reserve. Lightly grease grill rack with cooking spray. Preheat grill. Place breasts on grill. Cook covered with lid, basting frequently with marinade, until tender, approximately 5 to 6 minutes on each side