Preheat oven to 350 degrees Fahrenheit. Pat the beef dry with paper towels and sprinkle with the salt and pepper.

In a heavy six-quart roasting pan or Dutch oven, heat two tablespoons of the olive oil over medium-high heat. Add the pot roast and brown on all sides, about 15 minutes. Transfer the meat to a large bowl.

Add the remaining tablespoon oil to the pan and sauté the onions in the oil until tender, scraping up the brown bits on the bottom of the pot, about five minutes. Add the fresh mushrooms and garlic and sauté an additional three minutes. Add the wine and boil one minute, then add the broth, dried mushrooms, potatoes, and rosemary sprigs.

Return the meat to the pan. Bring the sauce to a boil. Cover and transfer to the oven. Braise until the roast is fork-tender, turning the meat over halfway through cooking, about two and a half to three hours.

Remove the roast from the oven and season the sauce with salt and black pepper to taste. Cut the meat across the grain into half-inch-thick slices. Arrange the sliced beef on a platter, garnish with rosemary sprigs, and pour the sauce with the onions, mushrooms, and potatoes over the meat. Serve warm.