Heat the smoker to 275F degrees with hickory and/or cherry wood.
Season the beef shanks on all sides with salt, pepper, garlic powder, onion powder and ground thyme.
Place on the smoker over indirect heat and smoke with the lid closed for 2 1/2 hours.
Place a large cast iron pot on the stove over medium heat. Heat the oil. Add the onions, celery, carrots and garlic and sauté, until tender. Add the remaining ingredients and stir to combine. Place the beef shanks in the pot.
Increase the smoker heat to 300F degrees. Place the pot on the smoker. Cover with a lid. continue cooking for 2 hours.
Using two forks, shred the beef, removing the gristle, fat and bones. Mix with the sauce, and serve over parmesan grits, polenta or pasta.