Preheat the oven to 400 degrees F or 200 degrees C.
Rub the red bell pepper with a little vegetable oil, place in a baking pan, and roast in the oven for 15 to 20 minutes, until the skin blisters. Leave the oven on, but remove the pepper and transfer to a bowl. Cover the bowl with plastic wrap and let sit for 10 minutes so skin will loosen. Peel the red pepper, remove and discard the seeds, then coarsely chop.
Season the chicken generously with salt and freshly ground white pepper. Heat the olive oil in a large ovenproof frying pan on high heat. Add the chicken legs, skin-side down, and sear for 2 to 3 minutes, or until golden. Turn the chicken over. Place the pan in the oven for about 25 minutes, basting with the drippings every 5 minutes, until done. Cook's Note: The juice should run clear when pricked with sharp knife. Remove the chicken from the oven and allow to rest so the juice stays in the meat.
To make the sauce: Place the stock, roasted red pepper, capers, olives, and garlic in large saucepan on high heat. Cook's Note: Do not use a small saucepan, as you will be reducing the sauce, and a larger surface area speeds this up.
Cook for about 3 minutes, or until the stock is reduced by half. Just before serving, gently stir in the mixed herbs, tomatoes, and oil. Season the sauce with salt and freshly ground white pepper.
Place a piece of chicken in each of 6 warmed bowls. Spoon the sauce over the chicken, making sure that each serving gets 2 tomato halves. Drizzle with a bit of extra-virgin olive oil over each serving.
NotesThis dish from Southern France is packed with flavour but is very light. This sauce also goes perfectly with halibut, sablefish, or lobster.