Cut the chicken into thin strips, about 2cm thick.
Grate half the garlic and ginger into a bowl, add the chicken, rice wine or sherry and 1 tbsp of the cornflour. Mix well and set aside to marinate.
Zest half a lemon and juice both lemons. Finely chop the shallot and chilli.
Heat the sesame oil in a pan over medium heat. Sauté the shallot for 1–2 minutes until softened, then add the remaining garlic, ginger and chilli and cook for 1 minute.
Add lemon juice and zest, stock, honey, 1 tbsp soy sauce, sugar and fish sauce. Bring to a soft boil, then reduce to a simmer and cook for about 15 minutes until reduced by half. Taste and add more soy sauce if needed.
Heat sunflower oil in a deep saucepan to 180°C.
Toss the marinated chicken in the remaining cornflour until well coated.
Fry the chicken in batches for 1½ minutes, remove and drain on clean kitchen towel or a wire rack.
Bring the oil back to temperature, then fry all the chicken again for 2 minutes until very crisp. Drain well.
Blitz the sauce until smooth, return to the pan and heat through.
Arrange the chicken on a serving plate, spoon over the sauce and finish with sliced spring onion and strips of lemon zest.
Serve immediately with rice or noodles.