In a bowl, combine pork cubes with baking soda, minced garlic, grated ginger, and soy sauce. Mix well and let marinate for 10-15 minutes to infuse flavor and tenderize the meat.
In a separate bowl, whisk together all the sauce ingredients. Make sure to dissolve the cornstarch completely. Set aside.
After marinating, season the pork with salt and pepper, then toss them in cornstarch to coat.
Heat half the oil in a skillet over medium-high heat. Fry the pork cubes until they turn light golden. Remove and set aside. This first fry is to ensure extra crispiness.
Add the remaining oil to the skillet and re-fry the pork cubes until golden brown and crispy. Remove and set aside.
In a large wok or pan, heat another tablespoon of vegetable oil over medium high heat. Add the onion and bell peppers and cook for 1 minute. Add the garlic and cook for another 30 seconds until aromatic.
Pour the sweet and sour sauce mixture in the wok and stir well until the sauce get thick and glossy. Add the fried pork and pineapple chunks to the wok, toss everything together well. Cook for another 2 minutes then remove from heat.
Dish it out hot over a bed of steamed rice or noodles.