Roast Beef with Mushrooms and Balsamic Vinegar
- Preheat the oven to 160˚C (325˚F).
- Rub the surface of the roast with the cream of mushroom soup mix. Place the roast on a rack in a small roasting pan. Roast uncovered for 2 hours or until the meat thermometer reads 68˚C (155˚F) for medium doneness.
- Place the roast on a cutting board and cover with aluminum foil. Let stand for 10 minutes. Heat the roasting pan on the stove over medium-high heat for 1 minute.
- Pour in the beef stock and scrape the bottom of the pan to loosen any stuck food particles. Add the mushrooms and simmer for 10 minutes. Combine the vinegar and flour. Using a wire whisk, thoroughly incorporate the mixture with the pan juices.
- Bring to a boil, stirring constantly until the gravy thickens. Season to taste. Slice the roast and serve with gravy and mashed potatoes.