Combine orange juice concentrate, soy sauce, garlic and ginger in a large bowl. Coat the chicken inside and out with the glaze and allow to rest for at least 2 hours in the refrigerator.
Prepare the Keg for indirect grilling at 300°F. Scatter soaked wood chips over the coals, and fill the diffuser kit with water.
Remove the chicken from refrigerator, season with salt and pepper and stuff herbs and orange and onion pieces into the cavity.
Place the chicken on the rack in the Keg, over the water tray filled with water and close the lid. Allow to cook for 3-3 1/2 hours, until the internal temperature reaches 170°F. Remove chicken from grill, tent with foil and let rest for 15-20 minutes before carving.