Philly Cheesesteaks

If using a whole steak, trim and cut steak crosswise with grain into roughly 3-inch wide sections, then set on large plate and freeze until firm but not frozen solid, about 1 hour. If using pre-sliced steak, skip to chopping instructions in Step 2. Serious Eats / Amanda Suarez Using a sharp knife, shave steak as thin as possible on a biased angle against the grain. Mound shaved meat on cutting board and chop coarse with knife, about 5 times for store-bought sliced meat or 10 times for hand-sliced. Serious Eats / Amanda Suarez Heat an empty 12-inch cast-iron skillet over medium-high heat for 5 minutes. Add oil to skillet and heat until just smoking. Add meat and onion in an even layer and cook, without stirring, until well browned on one side, 4 to 6 minutes. Continue to cook, stirring frequently to move and pull apart the meat slices until meat and onions are browned and meat is no longer pink, 2 to 4 minutes. Serious Eats / Amanda Suarez Stir in torn provolone cheese, Parmesan cheese (if using), salt, and pepper. Cook, stirring constantly, until cheese is melted and well combined, 1 to 2 minutes. Turn off heat. Divide mixture into 2 individual portions the length of the rolls. Shingle 2 slices of Provolone cheese over each portion. Cover and let cheese melt, about 1 minute. Serious Eats / Amanda Suarez Center rolls, cut sides down, over each portion of meat. Working with one at a time, use a large spatula to scoop under each portion of meat and flip meat into roll to create a filled sandwich. Serve immediately. Serious Eats / Amanda Suarez