Heat oil in a large skillet over medium high heat.
Pat roast dry with paper towels and generously season each side with salt and pepper. Place in skillet and sear each side of the roast for 2-3 minutes, or until browned.
Place roast in a slow cooker sprayed with nonstick cooking spray.
Place onion, carrots, potatoes and celery around the edge of the slow cooker. Pour Worcestershire sauce, red wine vinegar and balsamic vinegar over the top of the roast.
Pour beef broth over the vegetables. Cover and cook on low for 8-10 hours.
To make gravy, strain the juice from the slow cooker into a saucepan over medium-high heat. Whisk together cornstarch and water then whisk mixture into the saucepan. Bring to a boil to thicken. Serve over sliced roast.