Remove the chicken from the refrigerator about an hour before you’re ready to grill. Dry the bird and remove any giblets in the cavity. Place on a cutting board, breast-side-down, with the legs facing you, and use kitchen shears (or a sharp, heavy knife if you don’t have shears) to cut along both sides of the backbone.
Remove the backbone and open the chicken by pressing down on the thighs. Press down at the center of the breastbone with both hands to break it so that the bird can lay flat (you can also snip the breastbone with the shears). Snip off the wing tips (reserve along with the backbone for making stock).
Combine the salt, spices, and olive oil together in a small bowl to make a paste. Rub the paste all over the chicken and set aside.
Light the grill: Create a 2-zone fire. For charcoal, this means lighting the coals and moving them to one side of the grill when they’re hot; for gas, just turn it up to high on one side and leave it off on the other. Clean and oil the grates.
Place the chicken, skin-side-down, on the hot side of the grill and sear for 4 to 5 minutes, depending on how hot your grill is. Flip and sear again on the other side. Move the chicken over to the cooler side of the grill, close the lid, and cook, flipping every 10-15 minutes or so, for about an hour, or until the bird registers 165°F.
Remove the chicken from the grill, place on a clean sheet pan, and rest for about 20 minutes before carving and serving.