If you lost that customer, your manager would not be happy. And do you think challenging her will compel her to introspect?

Most probably not. She’d brand you and your restaurant rude and just ignore your opinion because she’s right in her mind.

What would be better, is to ask her how the food was after she’s eaten. If she praises the food, tell her a native Chinese chef made it and s/he was very good.

The customer may realise how her opinion of whether the food was good depends on something that doesn’t objectively affect the food itself.