We just Skyped with fermentation and ferment guru Sandor Katz in my Ecogastronomy: The Art and Science of Food class at Western Washington University. He had a lot of good advice and good humor about ferments—thank you, Sandor!
And, from me:
I store my sourdough starter in a loosely-covered mason jar in the fridge, and usually it does just fine for several weeks without feeding. It may look dubious, with the liquid separated at the top and no bubbling. But when I take it out, l let it warm on the counter at room temperature for a few hours, mix in the liquid layers and feed it some fresh flour* and water (say, 1/3 cup each), fermentation starts back up, it increases in volume, and it’s ready to feed more and use. Don’t lose heart if your little ferment hardly bubbles and it has only a faint fermentation smell. Usually, I can resuscitate almost any starter.
Fermented grain-breads in Paris
If for some reason our starter fails to resuscitate, we go to our favorite local sourdough expert, Drewsy Inglis, for a new batch. You can make your own, by leaving a wet batter of just flour and water open in the kitchen. The air has enough yeast spores floating around that it can innoculate your batter on its own. Or, you can buy commercial sourdough innoculants. Often, though, getting some proven starter from a friend is the best source. You don’t need much — a quarter of a cup, gradually bulked up with feedings, will give you all you could want.
Try it! The tangy taste of sourdough, and the simplicity of ingredients in sourdough bread—especially coarse and fermented grain flour, water and salt, and the starter which also is just flour and water—is a perfect mix.