Wash 1 kg of potatoes and place them in a saucepan. Cover them with cold water and add half of the salt.

Bring the potatoes to a boil. Cook for 20 minutes until tender when pierced.

Preheat the oven to 200°C / 390°F. Halve 600 g of white zucchini lengthwise.

Score the cut sides of the zucchini in a crosshatch pattern. Arrange them cut-side up in a baking dish.

Brush the zucchini with 1 tablespoon of olive oil. Roast for 35 to 40 minutes until golden and tender.

Chop the parsley, garlic, red bell pepper, and shallots. Put them in the blender with oregano and 2 tablespoons of olive oil.

Blend the chimichurri until finely chopped but not smooth. Set the sauce aside.

Drain the cooked potatoes thoroughly. Sprinkle them with 2 tablespoons of cornstarch and toss to coat.

Finely slice the onion. Heat 1 tablespoon of olive oil in a frying pan over medium-high heat.

Fry the potatoes and onion together until the potatoes are crisp. Cook until the onion is caramelized.

Heat the butter and remaining olive oil in a clean frying pan. Season the beef steak with the remaining salt.

Sear the beef steak until browned on both sides. Rest it for 5 minutes before slicing.

Divide the steak, crispy potatoes, and roasted zucchini between four plates. Spoon the chimichurri over the steak.