Fast food chain Boojum's owner has described a scramble to get foil wrapping for the Northern Ireland firm's Mexican burritos after a Brexit supply hitch.
David Maxwell, who took the business over with brother Andrew in 2015, said bowls for serving burrito fillings had also been held up in ports.
And the Monterey Jack cheddar-style cheese for its burritos is facing paperwork as it is sent over to Great Britain for shredding before coming back. Mr Maxwell said the business had pivoted towards contactless click and collect ordering, takeaway, delivery and meal kits as a result of the pandemic. Today it launches two ready meals - a beef chilli and bean chilli - to be sold through Henderson Group convenience stores like Spar.
Of Boojum's 17 branches in Ireland - including five in NI - 13 are currently trading.
While Marks & Spencer's fruit sweet Percy Pig was one of the first food products to be identified as a potential victim of complexities in the EU-UK Trade and Co-operation Agreement, Mr Maxwell said: "It's not just Percy Pigs but tens of thousands of products.
"A significant part of our supply chain consists of goods landed into Great Britain and shipped here. We're potentially having to divert supply so that goods aren't landed into Great Britain but land directly into NI or into Dublin so we can avoid the administrative burden or even the potential tariff burden although the product might only land in GB."
However, its vegetables are already imported into Dublin, while meat is sourced in Ireland. But he added: "There's no doubt there is an extra administrative burden from the GB landbridge and the paperwork required.
"While we're hearing from government that the product is flowing through ports, the problem is the product isn't getting to ports because the paperwork challenges are enormous."
But there were opportunities. "A great example is cheese. Our Monterey Jack is made in Ireland and is sent to GB to be shredded and then is sent back into as a finished product. So there are two times it effectively crosses the new trade barrier.
"Whilst there are no tariffs, there are administrative costs that are problematic. For us, that's one product we're looking at - how we can keep cheese on the island of Ireland and keep down those unnecessary costs."
Packaging has also been hit. "Pre-Christmas it seemed the whole global supply chain slowed down. People were stockpiling before Christmas and Brexit and you had the explosion in Beirut, and then Brexit came along," said Mr Maxwell.
"So we had containers that didn't come in and that affected some of our packaging so we really had to scramble the first week post-Brexit.
"The bowls were held up in containers in port due to a slowdown of global supply chain so we had to scramble so some customers may have seen different bowls than usual. Our foils were being sourced through a GB supplier and they were not as ready for Brexit as they should have been. We were then ringing nine different suppliers to supply us in GB.
"There was either a lack of stock or a reluctance to supply into NI so we are having to rethink foil. It's a unique product with a wax paper side and a foil side but we use millions every year so there are enough volumes there to make it interesting as a proposition to someone."
He added that the firm had faced "some dark, difficult days" in the pandemic. "We had to really figure out what was happening and figure out a plan. Thankfully I had a very strong team of people around me to help figure out a safe way of trading."