For the rub, in a small bowl, combine the pepper, brown sugar, paprika, garlic powder, and salt and mix well.
Rub the ribs with the spice mixture and transfer them to a covered roasting pan or Dutch oven. Pour beer around the beef (not over it), cover the pan, and cook over direct heat on the barbecue for 3 hours.
Remove the ribs from the pan and cut into individual portions. Transfer the ribs back to the grill, close the grill cover, and cook for 5 minutes longer, or until they are crusty and tender. Serve with chimichurri sauce.