Cut potatoes into 5mm half-moon slices and soak in water. Drain well.

Cut red bell pepper into bite-sized pieces and roughly chop zha cai.

Place potatoes in a microwave-safe container, cover loosely with plastic wrap, and microwave at 600W for 2 minutes.

Slice chicken breast diagonally against the grain and marinate with sake, salt, and pepper.

Heat sesame oil in a frying pan over medium heat. Add potatoes and chicken, stir-frying until chicken changes color.