Instructions

1. In a small bowl, combine parsley, garlic, red pepper flakes, oregano, and salt. Stir in olive oil and vinegar until well mixed. Set aside to let flavors meld.
2. Preheat a grill or grill pan over medium-high heat. Season the steak with salt and pepper on both sides.
3. Grill the steak for about 5-7 minutes per side, or until it reaches your preferred doneness (medium-rare is typically about 135°F).
4. Remove the steak from the grill and let it rest for 5 minutes before slicing it thinly against the grain.
5. While the steak is resting, slice the bread rolls in half and optionally toast them on the grill for 2-3 minutes until lightly golden.
6. To assemble the sandwich, spread a generous amount of chimichurri sauce on the bottom half of each roll.
7. Layer the sliced steak on top of the chimichurri, and top with sliced onions and additional chimichurri as desired.
8. Close the sandwiches with the top half of the rolls, slice in half if desired, and serve immediately.