Place meat in zip lock bag with flour. Seal and toss well to coat. Brown in oil. Layer ingredients in crockpot in this order: meat, carrots, potatoes, celery, onion, beef broth, tomatoes, garlic, thyme, mustard. Cook on high for 2-3 hours, then turn on low for about 4-5 hours or until tender. You can stir to mix ingredients after the first couple of hours.