Cut the chicken into 8 serving pieces: With a boning knife or chef’s knife, cut each leg off the chicken above the thigh bone. Then separate each leg into drumstick and thigh following the line of fat on the underside. With kitchen shears, cut out the back bone and discard. With a chef’s knife, cut through the breastbone so you have 2 breast halves with the wing attached. Cut across each breast to separate it into 2 pieces.
Pat the chicken dry and season generously with salt and pepper. Heat 2 Tbs. of the oil in an 11- to 12-inch straight-sided sauté pan over medium-high heat until shimmering hot. Working in 2 batches, cook the chicken until golden-brown, 3 to 4 minutes per side. (Reduce the heat to medium for the second batch if the brown bits sticking to the pan get too dark.) Transfer the chicken to a plate.
Pour off all but a thin layer of fat from the pan. Lower the heat to medium and add the remaining 1 Tbs. oil. Add the onion and a pinch of salt and cook, stirring and scraping up any browned bits with a wooden spatula, until the onion is tender and lightly browned, about 5 minutes. Add the red wine, raise the heat to medium high, and boil until the wine is reduced by half, 3 to 5 minutes. Tie the herbs together in a bouquet garni and add to the pan along with the tomatoes and their juice. Return the chicken pieces to the pan, turn to coat them in the sauce, and gently simmer, uncovered, turning the chicken occasionally, until just cooked through, 25 to 30 minutes.
Using tongs, transfer the chicken to plates or a serving platter. Remove the herbs and season the sauce to taste with salt and pepper. Spoon the sauce over the chicken, and serve.
In Italy, starchy dishes like polenta and pasta are typically served on their own as a first course, but if you’re being nontraditional, either would make a great accompaniment to this dish.