Cut broccoli into small florets and trim the root of shimeji mushrooms, separating them.

Slice chicken breast into thin pieces using a diagonal cutting method. Season with salt and pepper, then coat both sides with potato starch.

In a frying pan, add broccoli and 3 tbsp water. Cover and heat over medium heat until boiling, then cook for 1 minute. Remove broccoli and pat dry. Wipe the pan clean.

In the same pan, heat 1/2 tbsp salad oil over medium heat. Add shimeji mushrooms and sauté until softened, then push them to the side. Add the remaining oil and chicken, cooking until both sides change color.