1. Shape the steaks by wrapping tightly in plastic, refrigerate overnight to ensure a structurally sound shape.
2. Prep the fries by cutting skin-on russets into rustic fries. Boil them in salted water until pliable, then towel-dry and freeze until firm.
3. Make the chimichurri by pounding garlic, shallot, jalapeño, and salt together. Add parsley, olive oil, vinegar, and chile flakes. Adjust seasoning, cover until serving.
4. Build the crust on the steaks by seasoning with salt and coating with a mix of cornstarch and crushed peppercorns.
5. Sear the steaks in a cold pan, gradually heating until the peppercorns crackle, then continue searing on all sides on medium high heat.
6. Baste the steaks with butter, shallot, garlic, and rosemary during the final minutes of cooking, then rest the steaks.
7. Finish the fries by frying chilled potatoes at 375–380°F, adjusting heat as necessary until golden and crisp. Season immediately.
8. Finish and serve by tossing hot fries with garlic, parsley, and Parmesan. Slice steak and serve with chimichurri.
