I seriously love my San Francisco Sourdough Starter. I keep it in the fridge in a large green mason jar and "feed" it every week or two. It's made up of flour, live wild yeast organisms, and another live organism called a lactobacillus, which is what creates the sour flavor in sourdough and causes the bread to rise.
Live starter is very resilient. If you don't feed it for weeks or months, you can still bring it back. A tell-tale sign that your starter is feeling neglected and hungry is a layer of liquid on top of your starter. That's alcohol, a byproduct of fermentation. If that happens (which it will at some point). To bring it back, you simply "feed it!"
To feed your starter, add equal parts old starter + flour + lukewarm water. It will double in size within the next 6-8 hours following a feeding, so make sure the container you're using is less than half full. I usually mix ~4 oz starter +4 oz flour + 4 oz water in a 32 oz mason jar (with the seal cracked to allow for expansion). Beware- I have busted a few mason jars in my time!
If your starter is particularly neglected, you may have to "feed" it a few times to bring it back into an actively ripe health. You'll know when it's a healthy white color with bubbles rising and popping like pancake batter on a hot griddle. Caution: if it gets too foamy, that means it's past it's prime and needs to be fed again.
The perfect loaf of sourdough bread only needs healthy "well-fed and ripe" starter + water, salt, and flour.
1 cup (227g) ripe (fed) sourdough starter THAT'S BEEN FED IN THE LAST 5-7 DAYS
1 1/2 cups (340g) lukewarm water
2 1/2 teaspoons salt
5 cups (602g) King Arthur Unbleached All-Purpose Flour
Store the bread for a few days at room temperature, wrapped loosely in plastic; freeze for longer storage.
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