Yield: 1 sourdough starter

To make your own sourdough starter, you need only repeat what ancient bakers discovered entirely by accident. The precise measurements are not essential. You are reproducing a technique that is six thousand years old. Because microbial populations increase rapidly, demanding more and more food to stay alive, most modern descriptions for starting a starter advise you to discard some mixture daily to avoid doubling your feedings as the size of your microbial population also doubles.

500 grams white bread flour

500 grams whole wheat flour

Water, room temperature or 80°F (to speed things along)

Day 1. In a large bowl, mix together the white bread flour and whole wheat flour. This will be the food stock for your growing population of microbes. To rouse your microbes from their dormancy, place 100 grams of the flour mixture and 100 grams of water into a small bowl. Use your hands to mix them together.

Cover the bowl with a porous cloth or paper towel, held in place with a rubber band. Place the bowl in a warm location, out of direct sunlight, for three days, or until bubbles form on top of the mixture and the dough puffs. This will happen more quickly in warm temperatures.

Day 3. Remove the covering from the bowl. Discard or compost about 80 percent of the mixture. Feed it with 50 grams of the reserved flour mixture and 50 grams of water. Stir or mix by hand.

Cover the bowl with a cloth or paper towel. Place in a warm location, out of direct sunlight, for 24 hours.

Days 4–10 (more or less). At about the same time every day, repeat the steps from day 3. Depending on the temperature of your house and the serendipity of the species of yeast and bacteria that colonize your starter, after a week has passed, your culture should start to rise and fall every day. There will be bubbles of carbon dioxide visible throughout the starter and on the surface and a black liquid called hooch may begin to collect. It should begin to smell sour.

To bake or store. When your starter rises and falls with regularity and smells sour, it is time to take a couple of tablespoons of starter and infect a roughly 3:2 ratio of flour to water. For example, in a 1-quart mason jar, mix 1 cup of water with your starter. Stir. Then add 11/2 cups of flour. Mix. In 12 hours, it will be ready to use in a recipe. You may also put it in the refrigerator until you are ready to bake with it. Alternatively, you may divide it: use some to bake and store some for later. 

Reprinted with permission from Sourdough Culture by Eric Pallant, Agate, September 2021