Prepare the chimichurri: In a bowl, combine parsley, cilantro, minced garlic, red wine vinegar, and 50 ml of olive oil. Season with a pinch of salt and pepper. Mix well and set aside.

Prepare the chimichurri mayonnaise: Take half of the prepared chimichurri and mix it thoroughly with the mayonnaise until well combined. Refrigerate until serving.

Prepare the fries: Heat cooking oil in a deep pot or fryer to 175°C (350°F). Fry the cut potatoes in batches until golden brown and crispy, about 7-10 minutes per batch. Remove and season immediately with salt.

Season the steak: Pat the sirloin steaks dry with paper towels. Season generously on both sides with salt and freshly ground black pepper.

Cook the steak: Heat the remaining 50 ml of olive oil in a heavy-bottomed pan over medium-high heat. Once shimmering, add the steaks. For medium-rare, cook for 3-4 minutes per side

Rest the steak: Transfer the cooked steaks to a cutting board and let them rest for at least 5 minutes. This allows the juices to redistribute, ensuring a tender steak.

Slice and serve: Slice the steak against the grain into thick pieces. Arrange the sliced steak and crispy fries on plates. Serve with the chimichurri mayonnaise and a spoon of the remaining fresh chimichurri.

Garnish with a sprig of fresh cilantro if desired.