Place the beef cubes, chopped onion, carrots, celery, and potatoes in a slow cooker.
Add the minced garlic, salt, pepper, garlic powder, and onion powder to the slow cooker. Pour 3 ½ cups of beef broth over the ingredients.
Place the lid on the slow cooker, and cook for 7-8 hours on low heat.
Towards the end of the cooking time, whisk the cornstarch into the ¼ cup beef broth. Pour this mixture into the slow cooker and stir. Allow to cook for another 20 minutes or so to thicken the stew.
Top with fresh parsley if desired. Serve with gluten free bread or crackers.