Instructions

  1. In a large, heavy skillet, melt butter or margarine.
  2. Cook onions over medium-low heat until golden brown.
  3. Add the mushrooms and continue cooking until mushrooms are tender.
  4. Let sit until cool enough to handle.
  5. In a large bowl, mix the sirloin, salt, pepper, steak sauce, and onion-mushroom mixture.
  6. Form into 5 burgers.
  7. In same skillet, heat olive oil over medium heat.
  8. Dredge burgers in flour and cook until desired doneness, turning once.
  9. Add cheese (if desired) and melt atop burger.
  10. Top with a dollop of sour cream.