Heat a large skillet over medium-high heat. Add the canola oil.
Season the beef with salt and pepper on each side. Add to the hot pan and brown on each side. Transfer to a 5-quart slow cooker.
In a medium bowl, add all of the sauce ingredients and mix ketchup, onion, light brown sugar, Worcestershire, lemon juice, vinegar, a splash of water, mustard, celery, chilli powder and garlic powder.
Pour the sauce over the beef, so it's evenly coated.
Cover and cook on low for 8 hours. Shred with two forks.