Pat roast dry with paper towels. Season all sides generously with salt and pepper. Lightly dust with flour (3–5 lb roast). Peel and chop carrots, potatoes, and onions into large chunks. Mince garlic; ready thyme and bay leaves. Measure wine and beef broth. Preheat Dutch oven over medium-high heat with a thin layer of oil.

Heat oil in Dutch oven over medium-high until shimmering. Sear roast on all sides until deeply browned, 10–12 minutes. Remove and set aside. Add onions and celery with a pinch of salt; cook 8–10 minutes, stirring, until softened and browned. Scrape up fond. Add garlic, tomato paste, thyme, and bay leaves; cook 1 minute. Deglaze with red wine if using. Add beef broth and bring to a simmer. Return roast; arrange potatoes, carrots, and parsnips around it. Cover and transfer to a 325°F oven. Braise 3–4 hours (180–240 min). Done when internal temp hits 195°F and meat is fork-tender.

Remove Dutch oven from oven. Let roast rest in braising liquid 10–15 minutes to redistribute juices. Transfer to cutting board and slice against the grain into ½-inch pieces. Arrange on platter with braised vegetables. Skim fat from braising liquid if desired, pour sauce over everything, and serve immediately. Key mistake to avoid: slicing with the grain makes meat tough and stringy.