Season the steaks with salt to taste; cover, set aside and bring to room temperature.

Meanwhile, rinse parsley, pat dry, and pulse several times in food processor. Add garlic, pepper (if using), and Louisiana-style hot sauce and process until coarsely chopped. With processor running, add vinegar in a thin stream, then olive oil. You want the parsely finely chopped, but not in a paste. Set aside.

Pat the steaks dry with a paper towel. To pan-sear, heat a little oil in a 12-inch cast iron skillet over high heat. Cook the steaks in batches, adding more oil as needed, to desired doneness. Let rest 5 minutes, then slice across the grain. Place steak on a platter and spoon the parsley sauce liberally over.
Serve immediately.