48. San Francisco sourdough bread
Sourdough is as old as the pyramids and not coincidentally was eaten in ancient Egypt. But the hands-down American favorite, and the sourest variety, comes from San Francisco.
As much a part of NoCal culinary culture as Napa Valley wine, sourdough bread has been a staple since Gold Rush days. Once upon a frontier time, miners (called "sourdoughs" for surviving on the stuff) and settlers carried sourdough starter (more reliable than other leavening) in pouches around their necks or on their belts.
Thank goodness that's not the way they do it at Boudin Bakery, which has been turning out the bread that bites back in the City by the Bay since 1849.