Preheat oven to 300°.
On the stove top, preheat a large soup pot over medium heat and add about 2T olive oil.
On a large plate or the brown paper packaging, season the roast on all sides with 2t salt and 15 grinds black pepper and then coat the roast in 2T flour.
Add the beef to the hot pot, letting it sear on one side to a dark brown color, do not move it around in the pot
When browned well, flip the beef with tongs to brown the other side and add onion to start sautéing around the beef.
When the second side is browned and the onions soft, add the beef stock and stir.
Transfer the entire pot to the oven, covered, and cook for about 6 to 8 hours (can vary by oven), stirring and flipping the roast once or twice during the day. (Note: make sure to check on the roast in the last 1 or 2 hours, if you still have plenty of liquid, remove the lid for the final hour to thicken the sauce, if you don't have enough liquid, add a bit of water so the roast doesn't burn).
After 6 to 8 hours the meat will be extremely tender and can be shredded with tongs, while the liquid will have reduced leaving the beef in a dark sauce. Discard any large pieces of fat or gristle.
Serve with mashed potatoes and roasted veggies, over grilled bread, or on sandwich buns.