Betty Ann's Asparagus Casserole

Here is my daughter's favorite recipe. I have been making London Broil this way almost as long as I have been married, and that is over 30 years. Melt butter in skillet. Cook and stir onions and 1/4 tsp salt in the butter until onions are tender. Keep warm over low heat. Stir together salad oil, lemon juice, garlic, 1/2 tsp salt and the pepper; brush on top side of meat. Set oven control at broil and/or 550~ degrees. Broil meat 2-3 inches from heat about 5 minutes or until brown. Turn meat; brush with oil mixture and broil just until rare, 5 minutes longer. Cut meat across grain at a slanted angle into very thin slices; serve with onions. NOTE: A can of mushrooms can be added with the onions. Brisket meat can be substituted for the flank steak. My Seasoning: 1 part garlic powder, 1 part onion powder, 1/2 part ground black pepper. Mix well before adding to recipe.