For the chicken, combine the garlic, ginger, soy sauce, sesame oil and sugar together in a large bowl. Toss the chicken in this to coat. Leave to marinate while you makethe sauce.
For the Katsu Dip, heat the oil in a large sauté pan over low heat. Stir in the onion, garlic, ginger and coriander to the oil and let these soften for about 3-4 minutes.
Add the spices to this along with the flour and gently stir through the stock. Leave these to bubble for 15 minutes until reduced and thickened.
Cooking the chicken: heat the oil to 160˚C, in a large heavy based saucepan, mix the cornflour and flour together, dip the chicken pieces into the flour mixture to coat, dredging off any excess.
Fry for 5-6 minutes until golden and crispy. You may need to do this in batches as too many will reduce the heat of the liquid a little too much and the chicken won’t go crispy.
Once cooked, transfer to a tray lined with kitchen paper using a slotted spoon and sprinkle with a little salt.
Serve the crispy chicken with the katsu dip and crunchy cucumber.