In a bowl, mix the first 7 ingredients. Halve roast; place in a 6-qt. electric pressure cooker. Pour pepperoncini mixture over top. Lock lid; close pressure-release valve. Adjust to pressure-cook on high for 60 minutes. Let pressure release naturally. A thermometer inserted into beef should read at least 145°.
Remove roast; cool slightly. Skim fat from cooking juices. Shred beef with 2 forks. Return beef and cooking juices to pressure cooker; heat through. Serve on rolls. To make ahead: In a large shallow freezer container, combine the first 7 ingredients. Add roast; cover and freeze. To use, place freezer container in refrigerator 48 hours or until roast is completely thawed. Cook and serve as directed.
