A sourdough starter is a living culture of wild yeast and bacteria that you keep alive with regular feedings. It sounds fussy, and people make it sound fussier than it is. At its core it is just flour and water, and a little neglect rarely kills it.
Building one from scratch
Mix equal weights of flour and water in a jar and leave it loosely covered at room temperature. Each day, discard most of it and feed it fresh flour and water. Over a week or so it starts to bubble and smell tangy, which means the wild yeast has taken hold and it is strong enough to raise bread.
Feeding and the discard
- Feed it on a schedule when it is active, usually once or twice a day at room temperature.
- You discard part of it before each feeding so it does not grow endlessly and weaken.
- Save the discard for pancakes or crackers instead of throwing it away.
Storing it long term
If you do not bake often, keep the starter in the fridge and feed it about once a week. The cold slows it down so it can coast for days between feedings. A starter is more resilient than you think. Even if it grows a gray liquid on top, that is usually just hunger, not death. Pour it off, feed it a couple of times, and it bounces back.