Heat oven to 225°F. Line 15x10-inch pan with foil. Place wire rack on pan; spray rack with cooking spray.
Cut steak into 4 serving-size pieces. Place steaks between 2 sheets of plastic wrap or waxed paper; pound with meat mallet or rolling pin to 1/2-inch thickness. Season steaks with salt and pepper to taste. In shallow dish, mix 1/4 cup of the flour, 1 teaspoon salt and 1/4 teaspoon pepper. In another shallow dish, beat egg and 2 tablespoons of the cooking sauce with fork. Set aside remaining sauce. Place bread crumbs on sheet of waxed paper.
Dip steaks into flour mixture, coating well; shake off excess. Dip floured steaks into egg mixture, then in bread crumbs, turning to coat completely; shake off excess.
In 12-inch nonstick skillet, heat 1/4 cup vegetable oil over medium heat until hot. Cook beef in oil 12 to 14 minutes, turning once, until golden brown. Remove from skillet to wire rack; place in oven to keep warm. Add remaining 4 teaspoons flour to skillet, stirring and scraping up browned bits in pan. Gradually stir in remaining sauce until well blended. Heat to boiling, stirring constantly. Cook 1 minute, stirring frequently. Serve steaks with mashed potatoes and gravy.