Chicken Cacciatore

Season the chicken pieces generously with salt and pepper. Dredge the pieces in flour, coating them lightly and tapping off excess flour. In a wide, 5 quart braising pan, heat the vegetable oil with 2 tablespoons of olive oil until a piece of chicken dipped in the oil gives off a sizzle. Add as many pieces of chicken to the pan as will fit without touching. Do not crowd the chicken; if skillet is not wide enough to fit all the chicken, brown it in batches. Once all the chickens is browned, remove everything from the skillet; add the onions to the fat remaining in the pan and cook, stirring 5 minutes.
Pour the wine into the pan, bring to a boil, and cook until reduced by half, about 3 minutes. Add the tomatoes and oregano, season lightly with salt and pepper, and bring to a boil. Add the chicken to the pot, adjust the heat to a gentle boil and cover the pan. Cook; stirring a few times, for 20 minutes.
Meanwhile, in a large skillet, heat the remaining to 2 tablespoons of olive oil over medium-high heat. Add the mushrooms and peppers and toss until the peppers are wilted by still crunchy, about 8 minutes; season with salt
Stir peppers and mushrooms into the pan with the chicken. Cook, covered until the chicken and vegetables are tender, 10-15 minutes. Check the level of the liquid in the pan. There should be enough to barely cover the chicken. If necessary, add small amounts of water to maintain the level of the liquid as the chicken cooks.