The following is taken from
Sourdough: Bread of the Miners
by Peter Jay & Helen Evans
published by No Regrets Books
No publication date given
ISBN: 1-890930-03-2

Making your very own Sourdough Starter!

1 package active dried yeast
1 cup of unbleached white flour
1 1/2 cups warm potato water
1 tbsp sugar

Mix the ingredients thoroughly in a non-metal (glass, ceramic or if you must, plastic) container large enough to allow the mixture to double, or even triple (due to the dried yeast.) Let the mixture stand, loosely covered, for a day or two, until it is frothy and full of bubbles. The bubbling will begin shortly after you mix the ingredients, but it will take a longer time for the bubbles to permeate the mixture and for the sour smell characteristic of sourdough to develop. After the mixture has fermented and soured, stir it down and refrigerate. It will be better after it has aged a few days in the refrigerator, and after having been used and replenished for a few months there is hardly a detectable from "wild yeast" sourdoughs.

Expanding the Starter

To expand the amount of starter you have working, simply add equal amounts of flour and water, preferably a thick rich potato water, and some sugar to it, let it stand to ferment until it is bubbling and sour, then refrigerate. For the truest sourdough taste, allow the expanded starter to age in the refrigerator a day or two before you use it, but if you are more interested in the leavening than the flavoring qualities of the starter, you can use it at once.

Note from Kerry: There are two major requirements to creating your own sourdough starter. First is to mix the ingredients and follow the directions. Personally, I don't use potato water and very rarely put sugar in, just when I feel it needs it. But I have been working with it for almost 20 years. Until you achieve a Zen-like oneness with your starter, just follow the directions.
The second requirement is to think up some phoney-baloney story about how your starter came around the horn with the 49'ers or some far-flung region of Tibet. I'm not sure why, but people love to talk about their starters lineage, although I believe most of it is bunk.

There is much more fascinating information in the book. If there is an interest, I could scan a few pages and make them available in the near future.