Cut both sides of beef steak in diamond pattern 1/8-inch deep. Heat butter in 10-inch skillet over medium-high heat. Sauté onions and 1/4 teaspoon salt in butter about 4 minutes or until light brown; keep warm. Mix remaining ingredients; brush half of the mixture over beef.
Set oven control to broil. Broil beef with top 2 to 2 inches from heat about 5 minutes or until brown. Turn beef; brush with remaining oil mixture. Broil 5 minutes longer. Cut beef across grain at slanted angle into thin slices; serve with onions.