Place the sliced chicken into a bowl. Add the Chinese cooking wine, chicken stock powder, bicarb soda, Chinese five spice, salt, MSG (if using) and white pepper. Mix well and marinate for 20 minutes.
Make the spice mix: In a small bowl, combine the salt, sugar, white pepper, black pepper, MSG (if using), and Chinese five spice. Set aside.
In a separate bowl, whisk together the cornflour and self-raising flour. Gradually whisk in enough cold water or soda water until you have a smooth batter thick enough to lightly coat the chicken.
Heat oil in a deep frying pan, wok or saucepan to 160°C. Dip the marinated chicken into the batter, allowing the excess to drip off, then fry in batches until lightly golden and cooked through. Transfer to a wire rack or paper towel.
Increase the oil temperature to 180°C and fry the chicken a second time until deep golden and crispy. Set aside.
Heat a large wok or frying pan over high heat with a drizzle of oil. Add the garlic and cook, tossing for 10 to 15 seconds then add the chillies and spring onion and stir fry for 30 seconds until fragrant.
Return the crispy chicken to the pan and toss briefly.
Sprinkle over the combined spice mix, using as much or as little as you like, then toss until evenly coated.
Serve immediately with steamed rice and dumpling sauce if desired. Garnish with extra chopped coriander.