The Soho venue, at 37 Berwick Street, comes four years after the group's first and second permanent sites in Marylebone and Chelsea. It first came to London as a pop-up in 2012.
Head chef Siggi Gunnlaugsson will divide his time between the three sites.
(Photo: Founder Tomas ‘Tommi’ Tómasson)
As with the other two London sites, the Soho venue will serve burgers cooked on an American gas grill, which the group says helps ‘enhance the charcoal flavour’.
There will also be the usual salad side with iceberg lettuce and chopped onion, plus fries with homemade Béarnaise sauce.
It will also feature Tommi’s signature ‘offer of the century’ – a burger, fries and soda drink for £10.90.
In the UK, the group focuses on local produce, including meat from HG Walter butchers in London’s Barons Court, and bread from Millers Bakery in Merton.
(Photo: Tommi's Burger, Soho)
The interior aims to provide an informal atmosphere, with vintage-style, eclectic touches.
“If you stop to think about it, what’s in a burger?” says Tómasson. “It’s good beef, bread, lettuce and tomatoes with ketchup, mustard and a little mayonnaise.”
Tómasson fell in love with burgers while studying hospitality and restaurant management in the USA.
In 1981, he returned to Iceland and opened the first Tommi’s Hamburgers site, which he called the country’s ‘first fast-food chain’. It grew to six sites before he sold his share in the group and moved on to launch Iceland’s first Hard Rock Café in Reykjavik in 1987.
He then bought and renovated the Hotel Borg in 1992, which he went on to run for a further ten years.
In 2004, he opened the first Tommi’s Burger Joint in Reykjavik, and there are now seven in Iceland, two in Berlin, three in Denmark, one each in Sweden and Norway, and the three in London.
The group now has 17 sites worldwide, and there are also plans to open two more sites in Oslo later this year.