Authentic Brittany 100% buckwheat crepes made with pure sarrasin flour, water, and salt, fermented for flavor and cooked thin on a billig griddle until crisp and lacy at the edges.
In a large bowl, whisk buckwheat flour and sea salt. Gradually pour in cold water, beating with a wooden paddle for 5 minutes to incorporate air. Rest covered in fridge for at least 4 hours.
Whisk batter and add a splash of cold water if needed to achieve single cream consistency.
Heat a cast-iron griddle to 220°C and grease with salted butter. Pour a ladleful of batter and spread thinly with a wooden rozell. Cook for 2 minutes until underside is crisp and edges curl.
Flip galette, rub with a knob of salted butter, cook 1 minute more, and serve warm or fill with your choice of savory garnishes.