Fire your oven to pizza heat, then let the temperature fall to 475ºF-500ºF degrees.
Remove and discard any lumps of fat from the inside of the chicken. Brine chicken for 2-4 hours (recipe below) in refrigeration. Rinse the chicken and pat very dry inside and out.
Place the chicken breast side down on a flat surface. With a pair of poultry shears, split the bird lengthwise along the backbone. Open it out, and press down with the heel of your hand to flatten completely. Turn the chicken skin side up and approaching from the edge, slide a finger under the skin of each of the breasts, making 2 little pockets. Repeat by creating a pocket on the thickest area of each thigh. Shove a sprig of herbs and slivers of garlic into each pocket.
Season the chicken liberally with salt and the cracked pepper.
Using a sharp knife, make slits in the skin near the tail and tuck the wing tips in to secure. The bird should be as flat as possible to ensure even cooking.
In a large cast-iron skillet or clay casserole, heat the olive oil over moderately high heat. When hot but not smoking, place the chicken skin side down in the skillet. Weigh it down with fire bricks wrapped in foil.
Place in the center of the wood-fired oven and cook until the skin is golden, about 15 minutes. Listen for sizzling!
Remove the weights and using tongs (so as not to pierce the skin), turn chicken over. Replace the weights, add the tomatoes and shallots and return to the oven to cook for another 15 minutes.
To test for doneness, pierce the thigh with a skewer. The chicken is done when the juices run clear. You may need to keep the chicken in the oven for another 20 minutes or until it is tender and legs pulls easily from the breast.
Transfer to a platter and cover loosely with foil. Let it rest for at least 10 minutes or up to 20. Carve and serve warm or at room temperature.