The latest to join the growing hot dog craze is best known for its burgers - and Byron say their new addition is "a hamburger that thinks it’s a hot dog."
It's created by their burger supremo Fred Smith, who got inspiration from Father’s Office diner in Santa Monica, where they are famous for hamburger-hot-dog mash-ups. It features "Freddar cheese" - his own take on the American cheese which many demand on their burgers - and adds to that a 6oz hamburger, streaky bacon, pickles, onion, shredded iceberg, American mustard and Byron sauce.
It goes on the menu on 21 July - and will be there until the end of August at all their branches.
Photo by Paul Winch Furness