How to Make It
Preheat oven to 350°F.
Heat olive oil in a Dutch oven over medium-high. Sprinkle roast with 1/2 teaspoon pepper and 1/2 teaspoon salt. Add roast to pan; cook until browned, about 5 minutes per side. Remove roast from pan; set aside. Add garlic to pan; cook, stirring constantly, 1 minute. Add wine; cook until reduced by half, about 2 minutes, scraping bottom of pan to loosen browned bits.
Whisk together stock and flour in a small bowl. Stir stock mixture into wine mixture; cook, stirring often, until thickened. Stir in tomato paste, thyme, bay leaves, remaining 1 1/2 teaspoons pepper, and remaining 1 teaspoon salt. Nestle roast into stock mixture. Cover and bake at 350°F 1 hour and 30 minutes.
Remove pan from oven. Add turnips, carrots, celery root, onions, and 1 cup water; toss carefully with gravy. Cover and bake at 350°F until vegetables are tender and sauce is thick and glazy, about 1 hour. Coarsely shred beef; discard thyme and bay leaves. Top with parsley.
Slow Cooker Method Omit step 1. Prepare as directed in step 2, substituting a skillet for the Dutch oven. Place roast and wine mixture in a 6-quart slow cooker. Omit steps 3 and 4. Stir together stock and flour; pour over roast. Add vegetables and 1 cup water. Cover and cook on LOW until roast is tender, about 7 hours.