The Blue Bell, located on Horsemarket Street, has posted a video clip on its social media channels.
It appears to show a woman appearing to put a selection of condiments from a pot on the table into her bag.
These include a salt shaker and vinegar bottle.
Posting on social media, The Blue Bell said: “Wanted for a salt – well, maybe a vinegar and other sauces.
“It is hard enough without people stealing things.”
In an update, it added: “We think we have found the culprit.
“A few sauces came forward, and this is not her first time, so the law might ketchup with her again very soon.”