Preheat oven to 300°.
On the stove top, preheat a Dutch oven or large pot over medium heat and add about 2 Tablespoons of olive oil.
On a large plate or the brown paper packaging, season the roast on all sides with 2 teaspoons salt and 15 grinds of black pepper and then coat the roast in 2 Tablespoons of 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.
Cover and transfer the entire pot to the oven. 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 pieces of fat or gristle.
Serve with mashed potatoes and roasted veggies, over grilled bread, or on sandwich buns.