Defrost roast. Add to crockpot. (I sometimes cook frozen and it comes out just fine.)
Sprinkle Italian Dressing Mix over roast.
Add entire jar of pepperoncinis on top of roast, including juice. (You may use whole or sliced peppercinis.)
Cover and let cook 4-6 hours on high or 8-10 hrs on low. The roast is done when you are able to shred with a fork.
Shred beef and add back to crockpot. Stir.
I use Italian rolls, but any rolls/buns are fine too. For a little extra goodness, try putting butter, garlic powder, and a little mozzarella cheese on the rolls and broiling in the oven until lightly toasted.