Heat oil in 10-inch skillet over medium-high heat. If beef roast comes in netting or is tied, do not remove. Cook beef in oil about 10 minutes, turning occasionally, until brown on all sides.
Place potatoes, carrots, mushrooms, celery and onion in 4- to 5-quart slow cooker. Sprinkle with salt, pepper and thyme. Place beef on vegetables. Pour tomatoes, consommé and vegetable juice over beef.
Cover and cook on Low heat setting 8 to 10 hours.
Remove beef and vegetables from cooker, using slotted spoon; place on serving platter and cover to keep warm. Skim fat from beef juices in cooker if desired. Remove 1/2 cup of the juices from cooker; mix with flour in small bowl, using wire whisk, until smooth. Gradually stir flour mixture into remaining juices in cooker. Increase heat setting to High. Cover and cook about 15 minutes or until thickened. Remove netting or strings from beef. Serve sauce with beef and vegetables.