Sourdough is a simple wild ferment made from nothing but flour and water. You can start a batch today, use it in a few days, and keep it alive and bubbling … well … forever.
If you have the patience, enjoy the flavor of sourdough, and can commit to feeding your quiet new “pet” frequently, you can develop a vibrant colony of mixed yeasts and bacteria and keep it going indefinitely. There are stories of legendary, long-lived sourdough cultures — maybe yours could join their ranks. Some were smeared on handkerchiefs, dried, and brought across the sea when folks immigrated to America. Some, like San Francisco’s famous culture, are just the unique ecology of microorganisms from a certain place.
What fun flavors will your kitchen-ecology develop? There’s only one way to find out.
Let New York Times
best-selling author Sandor Katz 
guide you through the process and concepts you’ll need to tend to your sourdough and ensure it has a long and bubbly, er, happy, life. Here is an excerpt from his latest book, The Art of Fermentation
Sourdough – An Excerpt from The Art of Fermentation