Place all the ingredients for the beef in the slow cooker.
Cover and cook on low for 8 to10 hours, or until the meat is very tender. Use forks to shred the beef, then stir the beef into the juices.
In a large bowl, toss together the slaw ingredients.
To serve, remove a helping of the beef with a slotted spoon or tongs, place it on a warmed tortilla, and top with some cabbage slaw.