Place the chicken breast-side down on a cutting board and use kitchen shears to cut along both sides of the backbone to remove it.
Flip the chicken over and press firmly on the breastbone until it cracks and the chicken lies flat.
In a food processor, combine chilies, garlic, olive oil, vinegar, lemon juice, lemon zest, roasted bell pepper, paprika, oregano, salt, and pepper; blend until a smooth emulsion forms.
Place the chicken in a large glass dish and coat thoroughly with two-thirds of the marinade, reserving the rest for serving. Cover and refrigerate for at least 4 hours.
Preheat oven to 200°C (400°F) and line a baking sheet with parchment paper or a wire rack.
Position the chicken skin-side up on the rack and roast for 45 to 50 minutes, or until the thickest part of the thigh registers an internal temperature of 74°C (165°F).
Remove from the oven and allow the chicken to rest for 10 minutes before carving into quarters.