To prepare the sauce, heat the water, ketchup, soy sauce, vinegar, sugar, and salt in a pan and stir well. Once it has reduced a bit, set the sauce aside for later.

Chop the garlic and ginger, dice the onion and bell pepper, and cut the chicken into large pieces.

To marinate the chicken, mix the chicken, soy sauce, Chinese wine, and egg in a bowl, then coat it well with a generous amount of cornstarch.

Fry the chicken pieces in a good amount of vegetable oil over high heat until golden brown, then place them on paper towels to drain.

Start stir-frying by heating a splash of vegetable oil in a pan and frying the garlic and ginger.

When they start to smell fragrant, add the bell pepper and onion and stir-fry for a couple of minutes. Then add the pineapple and stir-fry for another minute.

Add the sauce we prepared earlier and a bit of cornstarch dissolved in water to thicken it slightly. Add the chicken, mix everything well, and it's ready to serve.