Heat oven to 300°F (150°C). Pat beef thoroughly dry and season with 1 teaspoon salt and the pepper. Heat oil in a 6-quart ovenproof Dutch oven over medium-high heat. Brown roast for 4–5 minutes on each broad side and briefly on its edges. Transfer to a plate.

Lower heat to medium, add onions and soften for 5 minutes. Stir in garlic and tomato paste for 1 minute. Add broth and Worcestershire, scraping the bottom clean of browned bits. Return beef and juices; add bay and thyme. Liquid should reach roughly halfway up the roast, not cover it.

Bring to a gentle simmer, cover tightly and transfer to the oven for 2 1/2 hours. Turn the roast once if convenient and check that a little liquid remains. Add hot water if the pot becomes dry; the oven should maintain a quiet braise.

Add potatoes and carrots around the meat, seasoning vegetables with remaining 1/2 teaspoon salt. Cover and cook another 60–90 minutes, until vegetables are tender and a fork twists easily in the beef. If vegetables finish first, remove them and continue braising the roast until tender.

Transfer roast to a board, tent loosely and rest 15 minutes. Remove herbs and skim excess fat from the liquid. For thicker gravy, bring juices to a simmer and whisk in optional cornstarch slurry; simmer 2 minutes.

Slice across the grain if the roast holds together, or pull into large pieces. Serve with vegetables and gravy. Allow up to 4 hours of cooking; a thick roast may need longer, so plan a little extra time rather than raising the oven temperature.