In a slow cooker, combine the stew meat, onion, celery, carrots, bay leaf and broth.
Cook the soup on low for 6-8 hours.
Remove the bay leaf. Stir in the salt and pepper, to taste.
If you'd like your soup to be a little thicker, combine the cornstarch and water in a small bowl. Whisk into the soup and let cook on low for a few more minutes.