Sprinkle steaks on both sides with ¼ teaspoon salt and 1/8 teaspoon pepper. Heat nonstick skillet over medium-high heat. Add steaks and cook 8 to 10 minutes for medium-rare or until desired doneness, turning steaks over once. Transfer steaks to platter; keep warm.
To skillet, add oil and shallot, and cook 1 minute, stirring often. Add mushrooms and remaining ¼ teaspoon salt and 1/8 teaspoon pepper, and cook until mushroom mixture is golden, 8 to 10 minutes, stirring frequently. Add port and ¼ cup water. Cook 30 seconds, stirring constantly. Spoon mushroom sauce over steaks.
