Pat the steak dry. Use paper towels to remove moisture so it sears better. Dry meat equals better browning and flavor.

Season generously. Rub both sides with 1–2 teaspoons olive oil, then sprinkle with kosher salt and black pepper. Let it sit at room temperature for 15–20 minutes.

Preheat the air fryer. Set it to 400°F (200°C) for 4–5 minutes. A hot basket helps create a nice crust.

Make the chimichurri. Finely chop parsley and cilantro. Mince the garlic. In a bowl, combine herbs, garlic, 1/2 cup olive oil, 2 tablespoons red wine vinegar, oregano, a pinch of red pepper flakes, 1/2 teaspoon sea salt, and black pepper. Stir and taste. Add more vinegar or salt if needed. Set aside to let the flavors mingle.

Cook the steak. Place the seasoned steak in the preheated basket. Air fry for 6–9 minutes total, flipping halfway. Thinner cuts like skirt may need 5–7 minutes; thicker sirloin may take 8–10.

Check doneness. Use an instant-read thermometer for accuracy: 125°F for rare, 130–135°F for medium-rare, 140–145°F for medium. The temperature will rise a few degrees while resting.

Rest the steak. Transfer to a cutting board and rest for 5–8 minutes. This keeps the juices where they belong—inside the steak.

Slice properly. For flank or skirt, slice thinly against the grain at a slight angle. This gives a tender bite. Sirloin can be sliced slightly thicker.

Finish with chimichurri. Spoon sauce over the sliced steak and let some soak into the meat. Add a squeeze of lemon if you like extra brightness.

Serve. Pair with roasted potatoes, a crisp salad, grilled veggies, or rice. Keep extra chimichurri on the table.