In a plastic storage bag, mix cornstarch, salt, and pepper. Add cubed beef and toss together until the beef is well-coated.
Place olive oil in the bottom of the slow cooker and add the beef.
Top with vegetables, bay leaf, and liquids.
Cover and cook on low for 6 to 8 hours.
Toss to coat in the gravy that forms. Serve over mashed potatoes or rice.