In a large skillet, heat oil over medium-high heat. Add roast and cook just until brown on all sides. Remove from heat.
Place roast and remaining ingredients (except cornstarch and cold water) into slow cooker. Toss to combine.
Cook on high for 4 hours or low for 8 hours. Remove roast and vegetables to a large bowl.
In a small bowl, combine cornstarch and water and stir until cornstarch is fully incorporated. Set aside.
Pour sauce from slow cooker into a saucepan and bring to a boil over medium-high heat. Add cornstarch and water mixture and stir constantly until thickened. Remove from heat.
Divide roast and vegetables onto 6 plates. Serve with gravy.
Recipe by Simple, Sweet & Savory at https://www.simplesweetsavory.com/slow-cooker-cola-pot-roast/