Basic Sourdough Starter

The same "Mother Dough" (sourdough starter) has been used at Boudin Bakery in San Francisco, CA since 1849.

What Do I Need?
1 small handful (1/4 to 1/3 cup) white flour
1 or 2 tablespoons of water

Tools:
a small bowl
a towel, napkin, or other piece of cloth
a large spoon

What Do I Do?
1. In a mound of flour, make a small well and add the water.
2. Slowly mix the flour and the water, bringing more flour into the center of the well. The mixture will gradually transform from a paste into a small piece of dough.
3. Knead this small piece of dough with your fingers for about 5–8 minutes, until it becomes springy.
4. Place the dough in a small bowl, cover it with a damp towel, and let it sit in a warm spot for 2 or 3 days.
5. When it’s ready, the dough will be moist, wrinkled, and crusty. If you pull off a piece of the crust, you’ll find tiny bubbles and smell a sweet aroma.
6. Throw away any hardened crust. “Refresh” the remaining piece by mixing it with twice the original amount of flour and enough water to make a firm dough. Set aside as before.
7. After 1 or 2 days the starter will have a new, fresh look. Remove any dried dough and mix with about 1 cup of flour.
8. Once again, cover the bowl with a damp cloth and leave it in a warm place for another 8–12 hours.
9. When the starter is ready, it will appear fully risen, and a small indentation made with a finger won’t spring back.

Now the starter is ready to be used in virtually any sourdough recipe. You can try it out on Berkeley sourdough.

Remember to save a small piece of the starter: You can put it in the refrigerator for several days, then refresh it again as above and use it to make another loaf. A good starter will serve you for years to come!

Source: Science of Cooking