Slice the chicken breasts into thin strips.
In a large bowl, blend the soya sauce and vinegar and then add the chicken. Leave to marinate for 30 minutes.
Remove the chicken strips and keep the marinade.
Cover a plate with flour and roll the chicken in it.
In a wok or a frying pan, heat some oil and fry the chicken. Pour in the marinade and cook until it is all absorbed.
Add the cashew nuts and cook for a further 1 to 2 minutes.
Add salt and pepper, then serve.