1 cup chopped celery
2 tablespoons olive oil
4 boneless, skinless chicken breast halves
1 tablespoon soy sauce
1 tablespoon tomato paste
1 teaspoon vinegar
2 tablespoons Worcestershire sauce
1/4 teaspoon garlic powder
2 large onions, thinly sliced
1/4 cup chopped fresh parsley
1/8 cup fresh basil
1/4 teaspoon crushed red pepper flakes
1/8 teaspoon ground black pepper
Heat oil in a large nonstick skillet over medium heat. Sear chicken breasts on both sides and lightly coat with 1 tablespoon olive oil; oil should be thick enough to extend up sides of breasts. Heat remaining olive oil in skillet over medium heat.
In a medium bowl, combine celery, olive oil, chicken, soy sauce, tomato paste, vinegar, Worcestershire sauce, garlic powder, onions, parsley and basil. Mix together and pour over chicken breasts.
Brown chicken on both sides and let cool; Heat oil in a large skillet over medium heat.
Bake 15 minutes, or until chicken is no longer pink and juices run clear. Remove breasts from skillet and refrigerate.
Serve chicken breast slices over chicken breasts in a large bowl and spoon celery sauce over each.