Generously season chicken breasts with salt and pepper. Coat with flour and shake off excess. Heat oil in a wide skillet (at least 10-inch diameter) over moderately high heat for about 1 minute. Add chicken and brown well on one side, get it pretty dark. Flip the chicken over and brown the other side. (Extra dark chicken makes a more delicious sauce.) Each side should take about 4 minutes. While the chicken cooks, prepare garlic. Remove chicken from skillet and set aside. Add thyme, garlic and white wine vinegar to the skillet. Stir to loosen whatever is stuck to the skillet. Add chicken broth, turn heat to high and boil rapidly until the lquid is reduced to about 1/4 cup. Pour over chicken and serve.