Optional: to brown beef, heat oil in a skillet, Dutch oven, or multi-functional cooker over high heat, and sear both sides of beef until well browned, about 3 minutes per side. Remove meat to a large slow cooker. Add pepperoncini brine to the skillet, and stir to loosen any browned bits; pour into the slow cooker.

If you skipped the browning step, now add meat and pepperoncini brine to the slow cooker. Drizzle water over meat. Sprinkle ranch dressing evenly over the top, then sprinkle au jus gravy mix evenly over. Top with butter slices and peppers.

Slow cook on Low until the meat is very tender and can easily be pulled apart, 8 to 10 hours.

Remove beef from the slow cooker, and shred the meat using two forks.

For sandwiches, preheat the oven to 400 degrees F (200 degrees C). Slice sandwich roll open, cover the open face with provolone cheese slices, and place on a baking sheet.

Bake in the preheated oven until the edges start to brown, about 7 minutes.