Marinate the pork by mixing pork cubes with salt, baking soda, white pepper, soy sauce, and Shaoxing wine. Let sit for 15 minutes.

Mix cornstarch and flour in a separate bowl. Pour beaten egg over pork cubes, mix, then coat each piece of pork with the flour mixture. Slightly squeeze each piece to ensure the pork is completely coated and packed.

Heat oil in a pan to 350°F (175°C) and fry pork until golden brown, about 4-5 minutes. Drain on a paper towel for a few mins. Heat the oil in the pan to 400°F (204°C) and fry the pork again for 1-2 mins. This ensures the pork is extra crispy.

To make the sauce, mix ketchup, vinegar, soy sauce, sugar, pineapple juice, and water together in a bowl. Set aside.

For the stir-fry, heat 1 tablespoon oil in a wok or pan. Sauté garlic, onion, bell peppers, and pineapple for about 2 minutes. Add the sauce and corn starch slurry and let simmer for 1-2 mins until the sauce has thickened. Add a pinch of salt to taste. Add the fried pork and toss everything together until well coated, about 30 seconds.

Transfer sweet and sour pork to a large plate and garnish with sesame seeds. Serve hot over steamed rice.