Rub steaks with 1 tsp. salt and 1/2 tsp. pepper. Cook steaks in hot oil in a large skillet over medium-high heat 4 to 5 minutes on each side or to desired degree of doneness. Transfer steaks to a serving platter, and keep warm.
Add garlic to skillet; sauté 30 seconds, stirring constantly. Add mushrooms and remaining 1/4 tsp. salt and 1/4 tsp. pepper to skillet; sauté 3 minutes. Stir in vinegar; cook, stirring frequently, 3 to 5 minutes or until mushrooms are tender. Spoon mushroom mixture over steaks, and serve immediately.
Pork Balsamico With Mushrooms: Substitute 2 lb. pork tenderloin, cut in 1/2-inch-thick slices, for steaks. Proceed with recipe as directed.