Grab yourself a big pot (one that can go in the oven) and put the chuck roast in it. Cover it with 4 tablespoons or so of Italian seasoning.
Cover the chuck roast with beef consomme and a half cup of water.
Put half the jar of pepperoncini on top. Pour out some the juice from the peppers as well. Season with salt.
Cover the pot and cook for 5 to 6 hours in a 275 degree oven. (You can also cook this in the slow cooker or slowly simmered on the stove). The beef should be falling apart. If it isn’t, keep cooking it until it does. When the beef is done, cool it down and put it in the fridge overnight. The fat will harden and skim it from the top.
Put the pot on the stove and heat on low to medium to heat through. If you need to, add more beef broth or water and add more liquid.
Toast a sub roll.
Cover the toasted roll with the shredded beef and a few peppers.
Cover with a few slices of cheese.
Put the sandwich under the broiler until the cheese melts.