The incident occurred in the St Helen’s Square area at around 4am on Sunday 5 April 2015.
Five or six men seemingly targeted the man and woman because they are from a foreign country.
The couple were on a night out and had left the Blue Fly Café Bar on New Street shortly before the attack.
It is alleged the suspects repeatedly punched and kicked the man, who is aged 24, over a period of 10 minutes.
He suffered a broken jaw, chipped teeth and bruising. He is now recovering following treatment at York District Hospital.
His girlfriend, aged 29, was repeatedly pushed to the ground while he was being attacked.
It is believed the only reason the suspects stopped the violence was because a passing taxi driver came to the couple’s assistance.
The suspects are described as white, aged between 20 and 25, short or shaved hair and spoke with English accents.
An E-fit has been developed of one of the suspects as part of the ongoing investigation.
Sergeant Adrian Carter, of the York Safer Neighbourhood Team, said: Extensive enquiries are ongoing trace up to six suspects who believe are from the York area. We hope the E-fit will encourage people to come forward with vital information.
If you know a local man who fits the description in the image, please contact the police or Crimestoppers as soon as possible. Any detail that could assist the investigation will be treated with the strictest confidence.
If you can help the investigation in any way, please contact North Yorkshire Police on 101, select option 2, and ask for Adrian Carter. Or email email@example.com
Alternatively, contact Crimestoppers anonymously on 0800 555 111 or through their Anonymous Online Form at www.crimestoppers-uk.org. No personal details are taken, information cannot be traced or recorded and you will not go to court.
Please quote reference number 12150055457 when providing details about this incident.