In a mixing bowl, combine the cornflour, half the salt, ground black pepper, and Chinese five-spice. Stir well to create an even mixture.

Take quartered chicken thighs and add them to the bowl with the cornflour mixture. Toss thoroughly to coat each piece evenly.

In a wok or large frying pan, heat vegetable oil over medium-high heat until it shimmers and reaches around 350°F (175°C).

Carefully add the coated chicken pieces in batches to the hot oil, frying for about 5-7 minutes per batch until golden brown and crispy.

In the same pan, reserve about 1 tablespoon of the frying oil, then add diced onion, sliced chillies, and minced garlic. Sauté for 2-3 minutes until the onion is translucent.

Combine the fried chicken back into the pan with sautéed vegetables and add the remaining salt and black pepper. Toss together for another 2 minutes.

Transfer Salt and Pepper Chicken to a serving platter and serve immediately for the best texture.