
In a small bowl, mix together all the sweet and sour sauce ingredients and set aside. Combine the ground pork or chicken with ginger, garlic, five-spice powder (if using), sesame oil, pepper, and salt. Stir until well combined. Wet both hands with water and shape the mixture into 24 meatballs. Set aside.
Heat a wok or skillet with some oil and pan-fry the meatballs until they turn light golden brown. Drain them on a plate lined with paper towels.
Clean the wok or skillet and heat it with a little oil. Add the onion and stir quickly for a few moments. Pour in the sweet and sour sauce and cook until it thickens, then add the meatballs. Stir well to coat the meatballs with the sauce. Dish out and serve immediately.