When Martha Stewart, who is something of a croissant connoisseur, first tasted these sourdough croissants, she knew they were something special. The recipe comes from Martha's niece, Sophie Herbert Slater. A self-taught baker, Slater set out to create her own version of sourdough croissants, inspired by the blog Baking Sense.
“Levain” is the French word for sourdough and in this recipe, it is the first step taken to make sourdough croissants: A specific amount of starter, flour, and water is mixed together, left to ferment overnight, then used completely in the baking process.
If you start the dough around 8 or 9 a.m., you should be able to make the dough, laminate, roll out, cut, and shape by late evening (saving you work in the morning). If you start later, roll and shape them the next morning.