Barts Exquisite London Broil

1. 1 pound beef flank steak
2. 2 medium white onions, thinly sliced
3. 1 teaspoon salt
4. 2 tablespoons unsalted butter
5. 2 tablespoons oil
6. 1 teaspoon fresh lemon juice
7. 1/2 teaspoon salt
8. 1 teaspoon freshly ground black pepper
9. 2 cloves garlic, crushed

Cut both sides of steak in a diamond pattern, 1/8 inch deep. Cook and stir onions and salt in butter until onions are tender. Keep this mixture warm. Mix remaining ingredients and brush half on one side of the beef. Broil 3 inches from heat for 5 minutes. Turn and brush with remaining oil mixture. Broil 5 more minutes. Cut across grain in thin slices. Serve with onions.