Toss halved potatoes with 3 tablespoons olive oil and salt on a sheet pan, roast at 425°F for 15 minutes.
While potatoes roast, whisk together minced parsley, minced garlic, vinegar, and remaining olive oil for chimichurri, then season steak generously with salt and pepper.
Push potatoes to the pan edges, add steak to center, and roast 8 minutes for medium-rare, let rest 3 minutes, then slice.
Serve steak with potatoes and drizzle everything with chimichurri sauce.
Photo: Diego Arenas de Rodrigo / Unsplash