Combine the broth, bean mix, salt, pepper, celery, carrots, garlic, onions, bay leaf, thyme and 2 cups water in a slow cooker. Cover and cook on low for 7 hours. Add the barley and, if the broth looks low, another cup of water. Cover and cook on low an additional 1 hour (8 hours total).
Just before serving, stir in the spinach to wilt. Serve in a big bowl with toasted crusty bread or baguette.
This recipe has been updated and may differ from what was originally published or broadcast.