In the Netherlands, they call this kind of loaf “Tijgerbrood,” or tiger bread, after the spotted look of the crust. The distinctive Dutch crunch crust has a dappled pattern, whose darkness will depend on how long the yeast has been allowed to rise.
To make Dutch crunch, a baker will brush unbaked loaves with a mixture of rice flour, yeast, sugar, salt, oil, and water.
You can get sourdough decorated with the crackle of Dutch crunch at Boudin Bakery if you want the ultimate Bay Area bread, but it’s more often found on sweet French rolls and served at a deli counter. Technically, the Dutch crunch is not a unique species of bread, but rather a topping that may be applied to any kind of loaf. Until recently, the Dutch crunch was largely unknown outside of the Bay Area and the Netherlands, but the rest of the world is starting to catch on. While Bay Area natives may take it for granted, it is as much of a local specialty as burritos or cioppino.