Dessert may be made ahead of time.
Sprinkle both sides of chicken with salt and pepper. In a large skillet brown chicken in olive oil over medium heat, 4-5 minutes each side. Remove chicken and set aside. Add mushrooms, onions and celery to pan and sauté in drippings from chicken until soft. Add chicken back into pan. Turn heat down to medium-low and add cooking sherry, Worcestershire sauce and Dijon mustard. Cook for 4-5 minutes until sauce is hot and mixed thoroughly. To make berry dessert, mash 1/4 cup of each of the berries, vanilla and lime juice. Evenly divide the berries between 2 bowls and top with sauce. (Make the dessert and let it sit at room temperature while you eat dinner.)