Sprinkle beef with salt and pepper. Heat oil over medium high heat. Add the beef and sear on all sides. In crock pot liner add beef, chopped onions, garlic, bay leaf, Worcestershire,tomato paste, hot sauce and broth. Place in slow cooker and cook on low for 4 hours, until the meat begins to fall apart with the pull of a fork.
Remove meat from slow cooker and slice into 1/4 inch slices or shred it. Ladle off the fat from the au jus and discard. Slather both sides of the bread with cheese and top with beef and onions. Serve with Au jus on the side.