Preheat your oven to 325°F (165°C).
Season the beef roast generously with salt and pepper.
Heat olive oil in a large oven-safe pot or Dutch oven over medium-high heat. Sear the beef on all sides until browned, about 4-5 minutes per side.
Remove the beef and set it aside. In the same pot, add the chopped onion and garlic, sautéing until softened, about 3-4 minutes.
Deglaze the pot with red wine (if using), scraping up any browned bits. Let it simmer for 2-3 minutes.
Add the beef broth, thyme, and bay leaves to the pot. Return the beef to the pot, ensuring it is partially submerged in the liquid.
Cover the pot with a lid and transfer it to the preheated oven. Roast for 2.5 to 3 hours, or until the beef is tender and easily pulls apart with a fork.
Remove the beef from the pot and let it rest while you prepare the gravy.
For the gravy, strain the cooking liquid into a saucepan, discarding the solids. Bring the liquid to a simmer.
Make a slurry by mixing cornstarch with water, then whisk it into the simmering liquid. Cook until the gravy thickens, about 2-3 minutes.
Serve the Hereford roast beef sliced, topped with the rich gravy.