Homeowners in London Fields have been waking to the sweet smell of onions being cooked on an industrial scale by their burger chain neighbours.

Hackney Gazette: Patty and Bun in Mentmore Terrace. Picture: Google MapsPatty and Bun in Mentmore Terrace. Picture: Google Maps (Image: Archant)

Patty and Bun makes all its food at its base in the Mentmore Terrace arches, but as the brand has grown and the volume of cooking has increased, an unpleasant side-effect has wafted into the area.

The firm says it tried everything to get rid of the pong, resulting in bosses recently splashing out £40,000 on a top-end filtration system, but neighbours say even that hasn’t worked.

The complaints began at the start of summer when people were opening their windows more, so the company started cooking them at night to see if that helped – and it didn’t.

“It’s pretty gross,” said one neighbour. “The pollution is a serious health issue and it’s not appropriate to cook at this level in a residential area.

Hackney Gazette: The new filtration system in Patty and Bun. Picture: Patty and BunThe new filtration system in Patty and Bun. Picture: Patty and Bun (Image: Archant)

“London Fields is being polluted by the cooking of 60kg of onions every night.”

Alex Notley, operations chief at Patty and Bun, said the night cooking was one of several attempts to fix the problem, and had now stopped.

“As of the first week of September and at considerable cost we have had an extensive filtration system fitted to our extraction which now completely eliminates any odour,” he told the Gazette. “Since its installation we have had no complaints and we no longer work through the night.

“We tried various things, different cooking techniques, to appease everyone. It’s been a massive upheaval but we’ve spent £40,000 on a filtration system about the size of a mini-van. I know onions are only one item on the menu, but they are a key one.

“I completely understand the complaints. We’re not one of those companies that just f***s off the local residents, and that has culminated in us spending a huge amount of money to fix the problem.”

A Hackney Council spokeswoman said officers had visited the restaurant after receiving a complaint.

She said: “They showed us measures they have taken to address the smell but if the problem continues we will consider enforcement action, if necessary, to resolve the issue.”