To thaw pastry, let stand at room temperature for 20 minutes. Or, thaw overnight in the refrigerator. Meanwhile, if using thje top loin steaks, cut each steak in half crosswise. In a large skillet brown tenderloin or top loin steaks in hot oil over med. Hight heat for 1 minute on each side. Drain on paper towels. Set aside. In the same skillet cook mushrooms and onions in hot butter and , m if desired, wine for 5 to 6 mintues til tender and liquid has evaporated. Remove skillet from the heat. Stir in thyme and pepper. Unfold pastry and place on a lightly floured surface. Roll into an 11" square. Cut into four 5 1/2 " squares. Place some of the mushroom mixture in the center of each square. Place a steak on top. Fold pazstry over meat. If necessary, trim pastry ot winin 1/2 " of the edge of meat. Reserve pastry trimmings. Turn bundles over. If desired, cut small shapes from trimmings; moisen with water and place on top of bundles. Bake bundles, pastry side up, on a rack ina shallow baking pan. Bake, uncovered, ina 425F oven for 18 minutes. Meat will be medium rare. Note that these may be frozen prior to baking for up to 3 months. To serve, unwrap and place, pastry side up, on a rack in a shallow baking pan. Bake, uncovered, in a 425F oven for 30 minutes. Meat wil be medium rare. If necessary, cover pastry loosely with foil during the last 5 minutes to prevent overbrowning.