Preheat flat top grill to 325˚F. Place steak sandwich meat on grill. Season with ¼ teaspoon garlic salt per portion. Sauté and chop meat until done.
Ladle ¼ cup spaghetti sauce onto each meat portion while still on grill. Mix meat with sauce to evenly coat.
Sandwich Build: Place two slices provolone cheese on top of meat. Allow cheese to melt. Slice ciabatta roll in half. Place one portion cooked meat, sauce and cheese on a roll. Place 1 teaspoon minced pepperoncino on top of cheese. Close sandwich with crown of roll.