Sprinkle both sides of meat with garlic salt.
Place in 3 quart (13 x 9) glass baking dish.
Cover with plastic wrap.
Microwave for 45 minutes on high.
Turn meat over; recover and Microwave for an additional 30 minutes on high or until fork tender.
Remove meat to platter; cover, and chill for several hours.
Dissolve onion soup mix in hot meat juices; set aside.
When ready to serve, slice meat and place in reserved seasoned juices in 3-quart (13x9) glass baking dish.
Microwave for 8-10 minutes on high or until heated through.
Let stand, covered, for 5 minutes before serving.