In a mixing bowl, combine cornflour, half of the table salt, half of the ground black pepper, and Chinese five-spice. Take your chicken thigh fillets and cut them into bite-sized pieces. Dredge each piece in the mixture, ensuring an even coating.

In a large non-stick pan, heat about 1/4 inch of vegetable oil over medium heat until it reaches 350°F (175°C). Carefully add the coated chicken pieces in a single layer, ensuring they don't touch to maintain crispiness. Fry for about 6-8 minutes, turning occasionally, until golden brown and cooked through. Remove and let drain on paper towels.

In the same pan, allow a tablespoon of oil to remain, and then add the chopped onion, red and green chillies, and minced garlic. Stir-fry over medium-high heat for about 2-3 minutes until the onions are soft and fragrant.

Add the fried chicken back into the pan with the sautéed vegetables. Toss everything together for an additional minute to combine the flavors.

Finally, stir in the freshly chopped spring onions and give everything a gentle toss. Serve hot, paired with steamed rice or noodles for a complete meal.