Season flour with salt and pepper. Dredge chicken in seasoned flour onto a sheet of wax paper. In a nonstick skillet, combine the vegetable oil and butter or margarine and heat over medium high heat until bubbly and hot. Add chicken and cook until lightly browned on both sides and cooked through, 3 to 4 minutes. Remove chicken and set aside.
To the same skillet, add the mushrooms and saute for about 5 minutes. Combine the water, broth mix, cornstarch, parsley, garlic powder, salt and pepper and add to the skillet. Cook, stirring frequently, until liquid is thickened, 1 to 2 minutes.
Return chicken to the skillet and cook until chicken is heated through, 1 to 2 minutes. Serve.