The operators of sushi chain which ripped off workers and "reverse-engineered" records to cover their trail have been fined a record $900,000.
Hero Sushi underpaid almost 100 workers in Canberra, Newcastle and the Gold Coast approximately $700,000, the Federal Court found.
Workers - many of whom were young migrants on international student and working holiday visas - were paid flat rates as low as $12-an-hour between April 2015 and July 2016.
Handing down penalties on Thursday, Justice Geoffrey Flick said the case was about "greed and the exploitation of the vulnerable".
"Those in a position to ruthlessly take advantage of others pursued their goal of seeking to achieve greater profits at the expense of employees," his judgement said.
"In doing so, a great number of false documents were deliberately and repeatedly created with a view to concealing the fraud being perpetrated. Lies were told to cover up the wrongdoing. It was only when the game was up that those responsible admitted their misdeeds."
The company deliberately chose not to provide staff with pay slips, to prevent them from being able to check their hours of pay, the court found.
One worker was paid $1000 per week for working more than 55 hours per week. Another worked between 50 and 60 hours a week, for between $13 and $15-an-hour.
One of the key figures at the centre of the case, Tommy Lee admitted to "reverse-engineering" records provided to the Fair Work Ombudsman when it was investigating the company.
"The provision of deliberately false records to the Fair Work Ombudsman was also part of the strategy to avoid scrutiny of the rates which had in fact been paid and to avoid scrutiny of the failure to pay loadings for weekends and public holidays," the judgement reads.
"The conduct in the present case, the Fair Work Ombudsman submits, 'is one of the most serious instances of false record keeping and production encountered by the applicant, and the most significant to be placed before the courts'."
Fair Work Ombudsman Sandra Parker said the fine was the largest ever imposed as a result of Fair Work Ombudsman litigation.
"This matter should serve as a warning for all businesses that underpaying migrant workers, who may be particularly vulnerable if they have language barriers or be reluctant to seek help due to their visa status," Ms Parker said.