Combine all ingredient except water & cornstarch in slow cooker (beef, onion, garlic, carrots, potatoes, broth, tomato sauce, soy/Worcestershire sauce, herbs, sugar, salt, and pepper). Stir all ingredients together.
Push all ingredients down to immerse it under the juices. Cover and cook the stew on Low for 8 hours or about 5-6 hours on High.
Whisk together the cornstarch and water until smooth. Stir into the beef stew, cover with the lid, and cook for about 5 minutes or until it slightly thickens the stew. Enjoy!