Add beef stock, garlic, oregano, seasoning, beer and onion to slow cooker on low. Make sure the onion slice is separated into rings. Stir together after heated through. About 30 mins or so. (You can also just use a pot on the stovetop. Just make sure it's super low heat.)

After the juice is completely heated add the beef slices one at a time. Mix them around in there with a fork once they're all added making sure every piece gets a bath. Leave for about 45 mins- 1 hour. Mix again then set slow cooker to warm setting till you're ready to serve.

Right before serving, butter both halves of the hoagie roll. Sprinkle with garlic powder, and a bit of oregano if you're feeling aristocratic, and put in broiler for approx 3 minutes, till it's toasted garlic bread not burnt. Remove, put cheese on the tops of the hoagie roll and put back in the warmed, but off, oven. Just to get a bit of melt on the cheese.

Place the beef from the slow cooker onto the cheesed half of the hoagie roll and make the sandwich. Spoon the juice from the slow cooker into a bowl for dipping. Boom. Done.