Season the chicken pieces with salt and cayenne. In a large cast-iron skillet, heat the oil. When the oil is hot, add the chicken and brown, cooking for 6 to 8 minutes on each side. Add the onions. Season with salt and cayenne. Stirring constantly, wilt and brown the onions, scraping the bottom of the pan to loosen any browned particles, about 10 minutes. Add the bell peppers and bay leaf. Continue stirring, again scraping the bottom of the pot to loosen any browned particles, for about 15 minutes. Add the water, cover, and reduce the heat to medium. Stir occasionally and cook for about 30 minutes, or until the chicken is tender. Add the corn, peas, and mushrooms, cover, and cook for 15 minutes more, stirring occasionally. Add the parsley. Remove the bay leaf and serve immediately.