Start by chopping your onion and mincing the garlic. Set them aside, ready for the slow cooker.
In the slow cooker, add the beef stew meat, chopped onion, minced garlic, beef broth, Worcestershire sauce, soy sauce, dried thyme, black pepper, and salt. Stir to combine everything evenly.
Cover the slow cooker and set it to cook on low for 7-8 hours or on high for 4-5 hours. The longer it cooks, the more tender the beef will become.
Once the cooking time is up, remove 1 cup of the cooking liquid from the slow cooker and mix it with 1 tablespoon of cornstarch and 2 tablespoons of water in a small bowl. Stir until smooth.
Pour the cornstarch mixture back into the slow cooker and stir to combine. Cover and cook on high for an additional 15-30 minutes, until the gravy has thickened.
Taste and adjust seasoning if necessary. Serve the beef tips over your favorite base, garnishing with fresh parsley if desired.