01 - Preheat oven to 325°F.
02 - Pat the beef roast dry with paper towels and season generously on all sides with salt and pepper.
03 - Heat a large Dutch oven or oven-safe pot over medium-high heat. Add a splash of oil and sear the beef on all sides until well-browned, about 4–5 minutes per side. Transfer to a plate.
04 - In the same pot, add onions, carrots, parsnips, celery, and garlic. Sauté for 5 minutes, scraping up any browned bits from the bottom.
05 - Stir in tomato paste and cook for 1 minute to deepen the flavor.
06 - Pour in the beer (if using), scraping up any remaining fond, then add the beef stock and Worcestershire sauce. Return the beef to the pot along with any accumulated juices.
07 - Add potatoes, bay leaves, thyme, and rosemary. Bring to a simmer.
08 - Cover the pot and transfer to the preheated oven. Cook for 2.5–3 hours, until the beef is fork-tender and vegetables are cooked through.
09 - Remove the beef and vegetables to a platter. Skim excess fat from the cooking liquid and discard bay leaves and thyme stems.
10 - Slice or shred the beef. Arrange vegetables alongside and ladle some of the cooking liquid over the top. Garnish with chopped parsley before serving.