Spray the bottom and sides of a 5 or 6-quart slow-cooker crock with non-stick cooking spray.
Season the beef with salt and pepper on all sides and place in slow cooker crock. Add all remaining ingredients cover, and cook on low for 8 hours.
When done cooking, remove lid and shred beef with two forks while still inside the slow cooker. Allow shredded beef to marinate in warm cooking juices for 5 minutes to absorb more flavor.
Serve with rice, tortillas, bolillo rolls, etc. as desired.