01 - Whisk together olive oil, lemon zest, lemon juice, garlic, oregano, salt, and pepper in a bowl until thoroughly combined.
02 - Place the spatchcocked chicken in a large dish or resealable bag. Pour marinade over chicken, coating evenly. Cover and refrigerate for at least 2 hours, or overnight for optimal flavor.
03 - Preheat barbecue to medium heat (approximately 375°F) for indirect cooking. Alternatively, preheat oven to 375°F if roasting indoors.
04 - Take chicken out of marinade, allowing excess to drip off. Discard remaining marinade.
05 - Place chicken skin side up on cooler side of grill (indirect heat). Close lid and cook for 40 to 45 minutes, turning once or twice, until internal temperature reaches 165°F at the thickest part.
06 - Finish chicken skin side down over direct heat for 2 to 3 minutes until golden brown and lightly charred.
07 - Transfer chicken to cutting board, tent loosely with aluminum foil, and let rest for 10 minutes before carving.
08 - Carve chicken and arrange on serving platter. Garnish with lemon wedges and fresh oregano sprigs.