Cut the chicken breasts into pieces about ½ cm thick.
In a bowl, combine the chicken pieces with corn flour and 1 tablespoon rice wine. Refrigerate while preparing the other ingredients.
Clean the leek and ginger root, then slice them into thin pieces.
In a small bowl, mix soy sauce with ½ tablespoon rice wine, salt and pepper to make the sauce.
Halve or quarter the walnut kernels according to your preference.
Heat a wok or large pan over medium-high heat and add the vegetable oil.
Once hot, add the walnuts and fry for 1 minute, stirring constantly. Remove with a slotted spoon and set aside.
Add the marinated chicken to the remaining oil in the pan and stir-fry for 1 minute until cooked through.
Add the ginger and leek slices and stir-fry for 1 minute.
Pour in the sauce and return the walnuts to the pan. Stir-fry for 1 minute until everything is heated through and coated with sauce, being careful not to let it brown too dark.