People ask me this more than almost anything else.
They look at the jar on my counter — bubbly, a little wild-smelling, nothing fancy to look at — and they want to know what it is. Some are a little suspicious of it, honestly.
But that jar is alive.
Flour, water, and something ancient
A sourdough starter is flour and water left to sit long enough for something to happen. And something always does. Wild yeast drifts in from the air, from the grain, from the hands that mix it. Friendly bacteria arrive alongside it. Together, they begin to feed, multiply, and work.
This is how all bread was made before commercial yeast existed. That jar on my counter is a direct descendant of something ancient.
What the bubbles are telling you
The yeast feeds on the natural sugars in the flour and produces carbon dioxide. Those are the bubbles you see. In a dough, those same bubbles create lift — the open, airy crumb that makes a good sourdough loaf what it is. At the same time, the bacteria produce mild acids that shape the flavor. That slight tang. That depth you won't find in a quick-risen loaf.
A kitchen pet
I think of my starter as a kitchen pet. I feed it regularly — fresh flour and water — and it rewards me. Every starter is shaped by its surroundings. The flour you use. The air in your kitchen. Even the hands that tend it. Mine has been fed in this bakery for years. It carries something of this place in it.
Temperature is the quiet variable
Temperature matters more than people realize. A warm kitchen speeds things up. A cool one slows everything down. Your starter will behave differently in July than it does in November. It's paying attention to its surroundings. It helps to pay attention too.
If yours has gone quiet
If your starter has been sleeping in the back of the refrigerator and gone quiet, don't worry. Feed it. Give it a warm spot. It will come back.
Starters are more forgiving than they seem. And once you understand what they're doing and why, they become less mysterious and more like an old friend you're just getting to know better.
And when feeding day leaves you with discard, don't toss it — put it to work in a sourdough cherry clafoutis.