Add cubed beef and cornstarch to a gallon sized freezer bag and shake well until the meat is well coated in cornstarch.
Add all the ingredients to the slow cooker, followed by the beef covered in cornstarch. Stir to combine.
Cover and cook on HIGH for 4 hours or on LOW for 8 hours.
If the sauce is too thin and you prefer a sticker, thicker sauce, mix 1/4 cup of beef broth with 2 tablespoons of cornstarch and add it to the slow cooker. Stir gently to combine and cook on low for another 30 minutes. The sauce will thicker as it simmers.