First, spatchcock the chicken by cutting out and removing its backbone, then opening the bird and flattening it out.
Lay the chicken in a large bowl or baking dish. Mix the marinade ingredients and pour the mixture over the chicken, making sure it's well covered top and bottom. Marinate for at least an hour, or as long as overnight.
Heat your grill until it's very hot and grease the grates well with oil. Place the chicken on the grill, skin side down. Weigh the chicken down with the special purpose round terracotta mattone, cast iron skillet, or one or more bricks covered in foil.
Grill the chicken until golden brown on both sides. This should take about 30-45 minutes for a smaller to medium-sized chicken.
Let the chicken rest for 10-15 minutes before cutting it into pieces and serving.