Add beef and all liquid/seasoning ingredients to the crock pot and set on high.
If you prefer to slice the beef, cook 3-4 hours, then remove beef from crock pot while still slightly firm and slice very thinly.
If you prefer shredded beef (easier), cook for 5 hours and shred with forks when tender, removing chunks of fat.
Preheat oven to 350 degrees.
Remove meat from crock pot, reserving juices, and pile meat on buns, topped with cheese.
Bake buns in the oven for 5 minutes, or until cheese has melted and buns warm.
Serve immediately with reserved juices (au jus) for dipping.