Pat the chuck roast dry and sprinkle each side with salt and pepper. Place the beef in the slow cooker and add the beef stock, onion soup mix and bay leaf. Cover and cook on low for 6-8 hours. Remove meat to a cutting board and let it cool for 5 minutes before slicing thin.

Pat the chuck roast dry and sprinkle each side with salt and pepper. Place the beef in the Instant Pot and add the beef stock, onion soup mix and bay leaf. Lift the beef up to make sure some moisture is under the cut of meat. Close the lid and place the vent to the "sealing" position. Hit "meat/stew" and let cook for 35 minutes for 1.5-2 pounds of meat and increase to 40 minutes for 2.5-3 pounds of meat. Let pressure release naturally. Once the pressure has subsided, remove meat to a cutting board and let it cool for 5 minutes before slicing thin.

When ready to serve, slice the rolls open. Place a piece of provolone cheese on one side of the bread and toast both pieces under the broiler until the cheese bubbles, then remove from the oven.

Place thinly sliced meat on the bread. Serve the sandwiches with a small bowl of warm au jus on the side.