Serious Eats, or you might have seen the recap here earlier, but this is the short version, pared down for use in my column in the Boulder Daily Camera - this version has a little less of the extras, with all the same how-to. Maybe a little easier to print out as a reference.
To make a sourdough bread – or any other sourdough creation, you need a starter. There are online sources for buying starters, but it’s pretty simple to build your own. All you need is flour, water, and a place to store your starter. A clean empty jar is perfect.
There are a few recipes that call for pineapple juice or potato water or raisins, but none of that is necessary. Flour, water, and time are all you need.
If your sourdough doesn't progress at the pace outlined in these instructions, don't fret. Some develop faster than others. It doesn’t mean there’s a problem; they’re all different, and that’s one of the great things about sourdough. Your starter is unique.
A sourdough starter is a simple concept—let some flour and water hang around for a while, and almost magically, the correct combination of yeast and bacteria will take up residence. That combination, when healthy and happy, creates an environment that's unfriendly to unwanted organisms.
One important thing to consider: it's a tradition among people who keep sourdough starters to name their starters. Yes, I’m serious.
A lot of starter instructions leave you with excess starter you’d discard. These instructions start with a very small amount of flour and water, so you don’t end up with too much before you’re ready to bake.
It's best to measure with a scale, but if you don't have one, you can assume that you can get 1/2 ounce of flour by dipping a one-tablespoon measuring spoon into your flour and pressing it against the side of the container to compact it. That will be close enough for this starter recipe.
On the first day, add 1/2 ounce of flour to ounce of water in your clean jar, and stir it up.
Cover the jar with plastic wrap and store it on the kitchen counter – this is how you will store it for the duration of the process.
Stir your starter on day 2 whenever you think about it. Once or twice is fine, or a dozen times during the day is fine. Leave it covered when you aren’t stirring. There’s no feeding today, but beginning on Day 3, you will feed every day.
Feed the starter with one ounce each of water and flour and stir it whenever you think about it. The more you stir, the faster you starter will develop, but you don’t need to be obsessive. Morning, evening, and bedtime is fine.
Feed your starter with one ounce of flour and half an ounce of water. Stir it, cover it, and leave it on the counter. Again, stir whenever you think about it. At this point, the mixture is half water and half flour, by weight. This is the ratio it will stay for the rest of the process.
At this point, you should see at least some bubbles in the mixture, and the scent may be changing. It’s not unusual for it to smell like buttermilk or sour milk.
Days 5 - 9
From now on, it's all about feeding once a day and stirring whenever you think about it. Unlike some recipes that require each feeding to double the existing amount of starter, I feed the same amount each day. Just add one ounce each of flour and water. If you don’t have the patience to measure precisely, don’t worry too much about it. Try to keep the mixture the same thickness, and it will be fine.
Some time between Day 8 and Day 10, the mixture will be ready for the first harvest, where you’ll take some starter out of the jar and use it to bake your first loaf of bread.
One thing to check out is whether the bubbles are just on top, or whether there are bubbles throughout the jar. After feeding and stirring, the mixture should rise in the jar within an hour after feeding. When the starter is very active it might double in size, so if you've got a small jar and a lot of starter, you might find starter crawling all over your counter top an hour or so after a feeding.
When the starter is that lively, it's ready to use in your baking.