Mix together black pepper, salt, and flour. Coat chicken breasts with seasoned flour.
In a large skillet, heat the olive oil. Place chicken breasts in the skillet and brown on both sides. Then remove chicken from skillet and set aside.
To the skillet, add wine and stir until the wine is heated. Add lemon juice, chicken stock, and mushrooms. Stir to toss, reduce heat, and cook for about 10 minutes, until the sauce is partially reduced.
Return the browned chicken breasts to the skillet. Spoon the sauce over the chicken, then cover and cook for about 5-10 minutes or until chicken is done.
Serve sauce over chicken. Garnish with chopped parsley.