Hanbaagaasuuteeki, the smash burger joint that turned Victoria’s lunch crowd upside down with its mash-up of American smash burger culture and Japanese, Korean, Thai and Vietnamese flavour, is celebrating its first birthday with five new additions to the menu.

Since opening on Buckingham Palace Road last year, the restaurant has built a cult following for burgers, or “bāgas”, that read like a culinary world tour: kimchi, katsu, gochujang, ponzu and nam jim all doing battle with a proper smashed patty and a soft potato bun. To mark twelve months in business, founder Fatih Alkan is adding five new bāgas and doggus (hot dogs to me and you) to the menu, each pushing the fusion further.

The five new dishes are:

Kimchi Bāga (£11) | the restaurant’s tangy, spicy calling card: a classic smash patty loaded with slow-fermented Korean kimchi.

Ika Ringu Doggu (£12) | made fresh daily until it runs out, this one packs crunchy calamari rings into a soft potato roll, finished with a ponzu-kuro nanban kick.

Kimuchi Doggu (£13) | not a traditional hotdog, and there’s no ketchup in sight: a bespoke sausage dressed entirely in Japanese-style kimchi.

Thai Okla Bāga 2.0 (£12) | a reworked take on the Oklahoma onion burger, piled with som tam-style slaw and a bold kra pao sauce.

District 4 Chicken Bāga (£14) | described on the menu as “straight outta Saigon”: crispy chicken thigh glazed in a fiery nem-style sauce, topped with punchy kimchi and fresh coriander.

“We started Hanbaagaasuuteeki because we wanted to put everything we love about Asian food into the format everyone already loves eating,” said founder Fatih Alkan. “One year in, the reaction has been completely mad in the best way. These five new bāgas are us pushing the idea further – more countries, more flavour.”

The new dishes join the existing menu of bāgas, doggus and “poteto” sides at Hanbaagaasuuteeki, 36 Buckingham Palace Road, Victoria, London SW1W 0RE, open daily from 11.30am until late.