Clean and dry the chicken. Cut it along the backbone to lay it flat (spatchcocking).
In a bowl, mix all the marinade ingredients thoroughly.
Rub the marinade all over the chicken, both inside and under the skin. Place it in a resealable bag or a bowl and let it marinate in the refrigerator for at least 12 hours, ideally overnight.
Before roasting, take the chicken out of the refrigerator and let it rest at room temperature for about 30 minutes.
Preheat the oven to 200°C (400°F). Place the chicken on a baking sheet lined with parchment paper, or on a wire rack with a pan underneath, skin-side up.
Roast for about 60-90 minutes, until the skin is golden brown and crispy and the internal temperature of the meat (near the thigh bone) reaches 80-82°C (175-180°F). You can baste it with the rendered juices from time to time.
Remove the roasted chicken from the oven and let it rest for 10 minutes to retain its juiciness. Then, cut it into portions.
Pollo a la Brasa is traditionally served with crispy French fries, a fresh salad, and the typical Peruvian green sauce, Aji Verde. You can also serve it with rice.