Chicken with Tomatoes and Peppers

1/ 4 cup plus 2 tablespoons extra virgin olive oil (90 ml)
1 chicken, about 3 1/ 2 pounds, cut into 10 pieces (1.575 kg)
Salt and freshly ground black pepper
2 ounces pancetta in 2 slices, cut crosswise into thin strips (60 g)
2 cloves of garlic, peeled and crushed
1/ 4 teaspoon hot red pepper flakes, or more to taste
1/ 2 cup dry white wine (125 ml)
2 1/ 4 pounds ripe tomatoes,* peeled; seeded gently, leaving a little liquid; and cut into slices (1 kg)
1 1/ 2 tablespoons chopped fresh marjoram, or 1 teaspoon dried marjoram or oregano
1 small onion, very thinly sliced
11/ 2 pounds green bell peppers, seeded and sliced in thick strips about 1 inch wide (675 g)
*If for any reason the tomatoes are not flavorful, add 2 teaspoons tomato paste when you add the tomatoes

Heat 1 / 4 cup of the olive oil in a large skillet over moderately high heat. Add the chicken pieces and cook, turning, until they are brown, 8 to 10 minutes. Season well with salt and pepper.
Reduce the heat to moderate and add the pancetta, garlic, and hot red pepper flakes to the pan. Cook, stirring often, until the pancetta is light brown. Pour in the wine and boil until it is reduced by half. Add the tomatoes and the marjoram. Reduce the heat to moderately low and simmer uncovered for 15 minutes, or until the sauce is thickened.
Meanwhile, in a separate skillet, heat the remaining 2 tablespoons oil and saute the onion over moderate heat, stirring often, until it is golden, 5 to 7 minutes. Add the bell peppers, raise the heat slightly, cover, and cook for 5 minutes, shaking the pan occasionally. Remove the lid and cook, stirring, until the peppers are tender but still firm, 4 or 5 minutes. (The onion will be very brown.)
Add the peppers and onion to the chicken and tomatoes and simmer, with the lid ajar, for 15 to 20 minutes. Taste for salt and pepper. Serve the chicken hot. This dish is one of those that are better the next day.