Combine sherry and next 5 ingredients in a small bowl; set aside.
Sprinkle both sides of steak with salt and pepper.
Place a large nonstick skillet over high heat. Coat pan with cooking spray; add steak, and cook 3 minutes. Reduce heat to medium-high; turn steak, and cook 3 minutes or until desired degree of doneness. Remove steak, and set aside.
Add sherry mixture, scraping bottom and sides of pan; cook over medium heat 1 minute, stirring constantly. Slice steak, and serve with sauce.