Combine potatoes, carrots, and onion in the bottom of a slow cooker. Place beef roast on top the vegetables.
Heat canola oil in a large skillet over medium high heat. Cook beef roast in the hot oil until browned completely. 2 to 3 minutes per side. Place beef roast atop the vegetables.
Stir tomato sauce, brown sugar, Worchester sure sauce, cider vinegar, and salt together in a bowl. Pour over the roast.
Cook on low for 10 to 12 hours or on high for 5 to 6 hours.
Remove roast and vegetables to a serving platter. Pour sauce into skillet and cook over medium high heat until thickened, 5 to 10 minutes. Serve with the beef and vegetables.