Mix broth and au jus seasoning together in your crock-pot. Add the round roast and sliced bell peppers. Sprinkle them with the packet of Italian seasoning.
Cover and cook on high for 4 to 5 hours or on low for 8 to 10 hours.
Remove the roast from the crock-pot and shred it with two forks. Return meat to the crock-pot.
Assemble your sandwiches by laying cheese on the bottom of the roll, topping it with meat and peppers, then adding pepperoncini on top. If you want, add a little of the cooking liquid to the top half of the sub roll, or you can serve the broth in a bowl to dip the sandwich in.
