Rub the entire tenderloin with olive oil. Season the tenderloin with salt. Roll the tenderloin in the cracked black pepper. In a hot saute pan, sear the tenderloin for 3 minutes on all sides for medium rare. Remove the tenderloin from the pan and allow to rest for 5 minutes before slicing. Spread each crouton with Creole Mustard. Slice the tenderloin into thin slices. Divide the beef into eighths. Start building the sandwich with the beef, cheese, onions, and peppers. Place the sandwiches on a platter and garnish with sprigs of fresh basil.