Turn on your oven to 350 degrees Fahrenheit, which is 175 degrees Celsius.
In a plastic bag, add your pepper, salt, and flour and stir together. Put one piece of chicken at a time into the bag, seal up the top, and shake the bag until the chicken is well coated in the mixture. Repeat for all pieces of chicken.
Put a skillet over medium heat and add oil. Once the oil is heated, put in the chicken and cook until the chicken is brown all over.
Grease a 9 by 13-inch baking dish and put the cooked chicken in it. Cover the pan with tin foil and put it in the oven for a 45-minute period.
While the chicken is in the oven, put the green bell pepper and the onion in the skillet you used for the chicken. Sauté until the vegetables are translucent, which should take 5 minutes. Put the brown sugar, the soy sauce, and the pineapple in the pan. Pour the cornstarch into the chicken stock and mix until there are no lumps. Pour this mixture into the pan.
Mix everything in the pan together and simmer the mixture for three minutes. It should thicken and become clear.
Remove the pan of chicken from the oven and pour the sauce that you have made over the top of the chicken. Bake another 10 minutes.