Classic San Francisco Sourdough Starter

Ingredients:
1 package active dry yeast
2 cups warm water (110 F or so)
2 cups flour

Directions:
Pour water into a container.
(It is best to avoid metal containers.)
Add yeast and stir until disolved.
Add the flour and beat until mixture is smooth.
If there are lumps repeat the beating in about 10 minutes.
Cover the container with cheesecloth
and place in a warm location overnight.
The starter is often called a sponge.
It can now be used.

To get authentic sourdough taste starter
should be kept going for long periods of time.
This means when some is used to make sourdough
bread then some of the ingredients
in the starter must be replaced.
Add equal parts warm water and flour.

After two days or so remove the cheesecloth,
cover the container and store
in the refrigerator until the next use.