1. Heat oven to 250 degrees.
2. Tear or cut mushrooms into bite sized pieces.
3. Cut onions into large chunks.
4. In a large Dutch oven or other heavy pot with tight fitting lid, heat 2 tablespoons of oil over high heat on the stove.
5. Brown the meat on both sides, taking the time to get a nice crust on the outside.
6. Season both sides of the roast with salt, pepper and garlic powder.
7. Scatter the mushrooms and onions over and beside the roast.
8. Pour in beer and vinegar and cover with the lid.
9. Braise in the oven 3-4 hours or until the beef is fork tender and the liquid has reduced.
10. Serve over mashed potatoes, rice, or creamy polenta.
Tip - when the meat is done, you can remove it and blend the mushrooms and juices to create a thick mushroom gravy. All of the steps are in the video below: