Cut the chicken breasts into 1-inch chunks and season with salt and pepper. Place the cornstarch in a large ziplock bag; add the chicken pieces and toss to coat the chicken evenly.
In a shallow bowl beat the eggs together. Heat the oil in a large skillet over high heat.
Dip the chicken pieces in the beaten eggs and place them carefully in the hot skillet (you will need to coat and cook the chicken in batches), and cook for just about one minute on each side, until golden and crispy, but not cooked through.
Add the chicken to a large rimmed baking dish. Bake at 400 degrees F for 12-17 minutes or until the chicken is cooked through.
Meanwhile, add the bell peppers and onion to the skillet and saute for 2-3 minutes. Add pineapple.
Mix the sauce ingredients together in a bowl and pour into the skillet with the veggies. Cook, stirring, until thickened.
Remove chicken from oven and pour sauce and veggies over the top. Toss to coat. Serve immediately with hot steamed white or brown rice.