1. Unfold the chicken thighs and lay them, skin side down, on a chopping board. (If some parts are very thick, lay your knife flat that slice them in half, parallel to the board. Use a sharp knife to make a few shallow crisscross cuts into the meat – this will help the flavors to penetrate. Then cut each thigh into bite-sized slices, an uneven ¼ inch or so in thickness. Place the chicken slices in a bowl.

2. To make the marinade, add the soy sauces and egg yolk to the chicken and mix well, then stir in the potato flour and lastly the oil; set aside while you prepare the other ingredients.

3. Combine the sauce ingredients in a small bowl; set aside. Use a pair of scissors to snip the dried chiles into ¾-inch pieces, discarding seeds as far as possible.

4. Heat enough oil for deep-frying to 350-400°F. Add the chicken and deep-fry until it is crisp and golden. (If you are deep-frying in a wok with a relatively small volume of oil, fry the chicken in batches). Remove the chicken with a slotted spoon and set aside. Pour the oil into a heatproof container, and clean the wok if necessary.

5. Return the wok to a high flame with 2-3 tablespoons of the oil. Add the dried chiles and stir-fry briefly until they are fragrant and just changing color (do not burn them). Toss in the ginger and garlic and stir-fry for a few seconds longer, until fragrant. Then add the sauce and stir as it thickens.

6. Return the chicken to the wok and stir vigorously to coat the pieces in sauce. Remove from the heat, stir in the sesame oil and then serve, sprinkled with scallion greens.