In a large shallow bowl, mix together the salt, sugar, white pepper, oil and cornflour slurry. Add the chicken pieces, turn to coat and let sit for 20 minutes.
Meanwhile in a medium bowl, mix together the butter, cream-style corn, water, caster sugar, salt and milk to make the sauce. Set aside.
Heat a large frying pan with 1 tablespoon oil over high heat. Stir-fry the onion with salt until soft, about 3-4 minutes. Stir in the chicken and fry until both sides turn brown, 3-4 minutes. Add the corn and stir well.
Add the sauce, mix well and allow to heat through, 1-2 minutes. Once boiling, cover and allow to simmer for 3 minutes. Serve hot.