1. Place cornstarch in a small bowl. Gradually add the wine, stirring to make a smooth paste. Stir in the remaining ingredients, except steaks.
2. Lay steaks in an 8-inch square baking dish. Pour mushroom mixture over them. Cover. Microwave at Time Cook (power level 10) for 8 to 10 minutes, or until steaks are done, rotating the dish 1/2 turn after 5 minutes. Let stand, covered, 5 minutes before serving.