The site at 103 Princes Highway may be reminiscent of an old paint shop but the inner workings are being transformed with something fabulous brewing, and new beer house Principal Brewing to open later in the year.

Co-founder of Papi's Ashley O'Neill said the latest COVID-19 inspired lockdown was a blessing with hundreds of burgers sold over their opening weekend of the truck.

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"We've only launched it on one [delivery] platform, Menulog, and it's just gone ballistic," he said. "The takeaway reach for that Fairy Meadow area covers down to Port Kembla and Dapto."

The former Mercedes school bus, now painted black, is offering Papi's signature burgers, chicken and fries like their Bacon and Cheese Burger with blue cheese sauce or Broccoli Burger with chipotle mayo.

Papi's Thirroul opened in December 2019 by Mr O'Neill and long-time mate Barry Pearson just a few months shy of the pandemic. However, the dive-bar on Lawrence Hargrave Drive has been another COVID-success story - largely because Mr O'Neill admitted they had no idea what they were doing.

"It was flailing, we were first-time business owners ... we just opened the doors and thought 'it will figure itself out' and it just did," Mr O'Neill said.

"When COVID-19 initially hit, we had the distinct advantage of not having a set business model. We didn't really have those limitations as we were just making it up anyway.

"Maybe we just got lucky every step of the way."

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This meant they could easily transition from serving shots to focusing on producing the greatest burgers they could (or "second best" according to their slogan), streamlining their delivery and trying their hardest to give staff shifts. Now business is flourishing with the launch of the bus just a small step in their grand plans.

"We're all pretty ambitious, we have big goals," Mr O'Neill said of his crew of business partners which has now grown to four.

"This bus is going to go on tour, whether it be down south or to Newcastle when the brewery opens," added Mr Pearson. "Then the aim is to renovate Papi's around October ... spend a bit of cash on it to make it a real fancy bar."

Illawarra businessman Steve Lozenkovski is now part of the Papi's team, with his side project being part owner of the new brewhouse. Once that venture starts serving the amber ale a second burger bus will be permanently parked out front, while the other Papi's mobile will "head on tour" to bring burgers to the masses around NSW and the country.

Papi's burger bus will be parked at 103 Princes Highway, Fairy Meadow from Wednesday to Sunday, 5pm to 10pm with the aim to eventually bring on lunchtime service.

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