Prepare Chimichurri Sauce: In a bowl, combine chopped parsley, minced garlic, red wine vinegar, olive oil, chopped chili (if using), dried oregano, salt, and pepper. Mix well and let rest for at least 30 minutes to meld flavors. Blend until smooth.
Preheat Oven: Preheat the oven to 180°C (fan mode).
Sear the Picanha: Heat a large pan with a drizzle of olive oil over medium-high heat. Lightly salt the picanha on all sides. Sear the picanha in the pan for about 2-3 minutes per side until a golden crust forms.
Prepare Roasting Tray: In a roasting tray, place bunches of rosemary, thyme, sage, and the halved garlic head.
Roast the Picanha: Place the picanha on a rack above the herbs in the tray so that the meat fat drips onto the herbs, creating a smoky effect. Optionally, lightly burn the herbs with a torch to intensify aroma. Roast in the oven for 30 minutes at 180°C fan.
Prepare and Roast Vegetables: Meanwhile, on a baking tray lined with parchment paper, arrange zucchini slices, red pepper strips, and eggplant slices. Drizzle with olive oil, season with salt and pepper, and toss to coat evenly. Roast in the oven for 20 minutes until tender and lightly golden.
Rest and Serve: Remove the picanha from the oven and let it rest for 10 minutes to retain juices. Slice the picanha and serve on a platter with the roasted vegetables. Garnish with chimichurri sauce.