Marinate the Chicken: In a medium bowl, combine the chicken chunks with 1 tbsp of light soy sauce, the shaoxing rice wine, and the white pepper. Mix well and set aside for at least 15 minutes to let the flavours meld.

Prepare the Coating: In a separate shallow dish, whisk together the cornflour and plain flour. In another bowl, beat the egg. Dip each piece of marinated chicken first into the beaten egg, letting any excess drip off, and then dredge it thoroughly in the flour mixture, ensuring it's fully coated. Set the coated chicken pieces on a plate.

Start the Sauce: While the chicken marinates, let's get the sauce going. In a large frying pan or wok, heat 1 tbsp of vegetable oil over a medium-high heat. Add the onion and bell peppers and stir-fry for 3-4 minutes until they begin to soften but still have a slight bite. Add the minced garlic and cook for another 30 seconds until fragrant.

Simmer the Sauce: Pour the reserved 150ml of pineapple juice, rice vinegar, 3 tbsp ketchup, 2 tbsp soy sauce, and the soft brown sugar into the pan with the vegetables. Stir well to combine and bring to a gentle simmer, allowing the sugar to dissolve completely.

Thicken the Sauce: Give your cornflour slurry (1 tbsp cornflour + 2 tbsp water) a quick stir, then slowly pour it into the simmering sauce while constantly whisking. The sauce will thicken and become glossy almost immediately. Turn the heat down to low, add the drained pineapple chunks, and let it gently bubble away while you cook the chicken.

Fry the Chicken: Fill a deep, heavy-bottomed pan or wok with about 5cm (2 inches) of vegetable oil. Heat the oil to 180°C (350°F). If you don't have a thermometer, a cube of bread should turn golden brown in about 30 seconds. Carefully add the coated chicken to the hot oil in batches. I find that cooking it in two batches prevents the pan from getting overcrowded. Fry for 4-5 minutes, turning occasionally, until the chicken is golden brown, crisp, and cooked through.

Drain and Combine: Use a slotted spoon to remove the cooked chicken from the oil and place it on a wire rack or a plate lined with kitchen paper to drain any excess oil. Once all the chicken is cooked, add it to the pan with the warm sweet and sour sauce.

Serve Immediately: Gently toss the crispy chicken in the sauce until every piece is coated. Serve straight away with fluffy steamed rice for the best texture.