Chef John's Steak Marinade

1 bottle beer
6 cloves garlic, crushed
1/4 c brown sugar
4 onions
2 c mushrooms, sliced
  1. Mix above ingredients. Place in bowl or plastic bag and add steaks.
  2. Cover steaks well and refrigerate for 1 hour.
  3. Remove steaks and let set at room temp for 1/2 hour or so.
  4.  Sautee onions and then add mushrooms and sauté until slightly browned.
  5. Season with salt and pepper.
  6. Grill steaks to desired doneness and serve with sautéed onion and mushrooms.