In a medium bowl, combine the pork cubes, soy sauce, Shaoxing wine, and white pepper. Toss well to coat. Let marinate at room temperature for 20 minutes.

In a small bowl, whisk together the ketchup, rice vinegar, sugar, pineapple juice, and soy sauce until the sugar is mostly dissolved. Set aside.

In a large bowl, whisk the cornstarch, all-purpose flour, and baking powder. Add the beaten egg and slowly pour in the ice cold water, whisking until a thick, pancake-like batter forms. Add the marinated pork cubes into the batter and stir to ensure every piece is completely coated.

Heat the neutral oil in a wok or Dutch oven to 350°F (175°C). Carefully drop the battered pork cubes into the oil one by one to prevent sticking. Fry in batches for 4-5 minutes until lightly golden. Remove with a slotted spoon and drain on a wire rack. Let the pork rest for 5 minutes.

Increase the oil temperature to 375°F (190°C). Return all the pork to the oil for a second fry. Cook for 1-2 minutes until deeply golden brown and very crispy. Remove and drain on the wire rack.

Carefully drain the frying oil, leaving about 1 tablespoon of oil in the wok. Heat over medium-high heat. Add the minced garlic and ginger, stir-frying for 30 seconds until fragrant.

Add the bell peppers and onions to the wok. Stir-fry for 2-3 minutes until they begin to soften but still retain their crunch. Add the pineapple chunks and toss to combine.

Pour the sweet and sour sauce mixture into the wok. Bring to a simmer. Give the cornstarch slurry a quick stir, then pour it into the sauce. Simmer for 1 minute until the sauce becomes thick and glossy.

Turn off the heat. Immediately add the crispy pork back into the wok. Toss rapidly until every piece of pork is beautifully coated in the sticky sauce. Serve immediately with steamed rice.