Tomos Parry's debut restaurant is due to open tomorrow in Redchurch Street, London.
The former Kitty Fisher's chef will offer a menu inspired by the Basque country, focusing on a "gentle and simplistic style" of cooking.
The menu features snacks including Carmarthen ham; cheese; grilled baby peas and wood fire grilled breads, made using organic native heritage grain flour.
Cedar wood sea trout with Jersey cream and river herbs; slow grilled red mullet; and offal hot pot with laverbread and potatoes (based on the Welsh national dish of Cawl) will follow.
The ingredients will be sourced from UK farms including Maerdy farm in South Wales while the wine list will be put together by Keeling Andrew & Co, the new wine import company set up by the founders of Noble Rot.
Parry said: "Brat will focus on fire cooking recognisable from Getaria, which generally means buy well and don't ruin it. Since leaving Kitty's, I've been working closely with farmers and fisherman to create a menu which is structured around native ingredients at the peak of their season.
"For me, the simple pleasure of eating well is what BRAT is all about. It's a place I would want to eat - whether that be one dish with a glass of wine at lunch or settling in at the bar for a few hours."
Welsh-born Parry trained under Grady Atkins at Le Gallois, Cardiff. He moved to London aged 25, beginning his professional career at the River Café, Hammersmith. Before opening Kitty Fisher's, in Mayfair, he worked in top restaurants such as michelin-starred Kitchen Table in Fitzrovia and the Climpson's Arch in Hackney.
In 2014 he won chef of the year at the Young British Foodie Awards and Best Breakthrough Chef at the Food and Travel Awards in 2015. He was also included in the Evening Standard's 2015 1,000 Most Influential Londoners.
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