Freeze steak 30 minutes, then slice very thinly against the grain with a serrated knife and season with salt and pepper. In a nonstick skillet, heat oil and cook onion until browned and beginning to soften. Transfer onion to a bowl and wipe skillet clean. Cook steak until cooked through and browned around edges. Gather meat into center of skillet and top with onion and several slices provolone. Cook until cheese melts. Serve on a toasted roll.