How to Make It
Preheat the oven to 375°. Season the chicken cavities generously with salt and pepper. Tuck a lemon half, 2 shallots, 2 garlic cloves, 1/2 bunch of tarragon and 2 thyme sprigs into each chicken cavity. Tie the legs together with kitchen string. Set the chickens in a large roasting pan or on a rimmed baking sheet. Rub the chickens all over with the 1 tablespoon of olive oil and season with the herbes de Provence, salt and pepper.
2. Roast the chickens in the middle of the oven for 30 minutes. Add 1/2 cup of the water to the roasting pan and roast the chickens for about 50 minutes longer, basting them occasionally with the pan juices; rotate the roasting pan as necessary to cook the birds evenly. The chickens are done when the juices run clear when a thigh is pierced with a knife or when an instant-read thermometer inserted in one of the thighs registers 165°.
Preheat the broiler. Broil the chickens for about 5 minutes, rotating the roasting pan, until their skin is golden and crisp. Transfer the chickens to a large cutting board.
Pour any pan juices into a small saucepan and skim off the fat. Set the roasting pan over 2 burners, add the remaining 1/2 cup of water and simmer over moderate heat, using a wooden spoon to scrape up any browned bits on the bottom of the pan. Add the liquid to the pan juices in the saucepan and boil until reduced to 1/2 cup, about 5 minutes. Keep the pan juices warm.
Peel 12 of the oven-dried tomato halves and coarsely chop them. In a medium bowl, mix the tomatoes with the Dijon and whole grain mustards, vinegar, honey, warm pan juices and the remaining 1 tablespoon of chopped tarragon. Whisk in the remaining 1/4 cup of olive oil and season the vinaigrette with Tabasco, salt and pepper.
Spoon half of the oven-dried tomato vinaigrette onto a large platter. Quarter each of the chickens and arrange the pieces on the platter. Arrange the 12 remaining oven-dried tomato halves around the chicken and serve right away, passing the remaining tomato vinaigrette at the table.