Put the cornstarch in a bowl and the beaten eggs in another bowl. Lightly season the chicken with salt and pepper. Dip the chicken pieces into cornstarch, coating all sides, and then dip them in the beaten eggs. Heat the oil in a large skillet over medium high heat. Brown the chicken on all sides in batches, being careful not to overcrowd the pan. Transfer the chicken to a paper towel-lined plate. Add the bell peppers to the skillet and cook for 4-5 minutes. Add the green onions, stir to combine, and add the chicken and pineapple. In a bowl, combine the sugar, pineapple juice, vinegar, ketchup, soy sauce and garlic powder. Stir until the sugar is dissolved. Pour the sauce into the skillet and stir to coat the chicken and vegetables. Bring to a boil, reduce the heat to medium, cover, and simmer for 10 minutes, stirring a couple of times. Serve immediately with steamed rice.