The operators of a Launceston takeaway restaurant have been fined $100,000 for underpaying a Chinese chef and creating false wage records.

The Fair Work Ombudsman found David and Priscilla Lam, who own Dave's Noodles in Launceston, created false records to pay a staff member for a 38-hour week when he worked 60.

It resulted in the Chinese chef being underpaid $86,000 over a four-year period.

The couple convinced the chef, who they sponsored on a 457 working visa, he had to sign the false time and wage sheets for immigration purposes.

The Federal Court fined the pair $100,000 and ordered them to repay the employee.

The couple are also the franchisors of the Dave's Noodles restaurants in Hobart, Burnie, Kingston, Moonah and Mowbray.

The chef's case was investigated by the Fair Work Ombudsman after the worker lodged a complaint via an interpreter.

The inspectors discovered he was being paid a flat rate based on a 38-hour week while being required to work 60 hours a week.

Judge Norah Hartnett described the couples' fraudulent paperwork as "particularly disturbing behaviour, worthy of significant reprimand".

He said the chef was in a vulnerable position, having to rely on the couple's favour to stay in Australia.

Fair Work Ombudsman director Craig Bildstien welcomed the penalty, saying it sent a clear message.

"This is a business that has blatantly ripped off a vulnerable overseas worker to the tune of $86,000," he said.

"It's important for the Fair Work Ombudsman to build a culture of compliance with workplace law and part of the way we can do this is to ensure that those who want to rip off staff and falsify records pay a price.

"I think this business will have to sell a lot of bowls of noodles now to make up a $100,000 court penalty."