An unhinged man randomly slugged an Asian woman in the face, knocking her to the ground, in a brazen attack outside a Chinatown restaurant on Monday, police said.

Surveillance video posted on Twitter by Assemblywoman Yuh-Line Niou, whose district covers Chinatown, captured the horrifying daytime assault on Bayard Street, near Mott Street.

The 55-year-old victim can be seen walking by the Kong Sihk Tong café at around 6:15 p.m. — when a man in an orange hoodie and denim jacket whacks her unprovoked.

The woman falls backward onto the pavement, and the attacker begins ranting as two people dining outside sit in stunned silence, the footage shows.

A man then rushes over to check on the victim, whose back was leaning up against a column of the eatery’s outdoor dining setup.

“Are you OK?” he asks — but the woman doesn’t respond or move, according to the footage.

She was brought to NewYork-Presbyterian Lower Manhattan Hospital in stable condition, police said.

Niou said the victim was “conscious and cognizant and alert.”

The suspect in the brutal assault was taken into custody and brought to Bellevue Hospital for a psychiatric evaluation, according to law enforcement sources.

Charges against him were pending.

“Things are being investigated and the hate crimes task force has been called in,” the assemblywoman tweeted.