Remove feathers, giblets, and excess fat. Spatchcock the bird by removing the backbone for even cooking.
Combine olive oil, balsamic vinegar, citrus juice, garlic, thyme, rosemary, oregano, and brown sugar.
Coat the bird with the marinade and let it rest for 2–4 hours in the refrigerator.
Set up for direct heat (for searing) and indirect heat (for cooking).
Grill on high heat for 5–7 minutes per side until the skin is crispy.
Move to a cooler area of the grill, close the lid, and cook until internal temperature reaches 165°F (74°C).
Brush with remaining marinade every 10 minutes.
Use a meat thermometer in the thickest part of the bird (should read 165°F)
Remove from the grill and let rest for 5–10 minutes to retain juices.