These sourdough starter recipes are from my friend Lisa M.:
Sourdough Starter
Dump into a glass bowl:
2 cups thick potato water
2 Tablespoons sugar
2 cups flour (more or less)
1/2 tsp. yeast (optional)*
Boil potatoes with jackets on until they fall to pieces. Lift skins out; mash potatoes making a puree. Cool. Add more water to make sufficient liquid, if necessary. The richer the potato water, the richer the starter. Put all ingredients in bowl. Beat until you have a smooth creamy batter. Cover. Set aside in warm place to start fermentation (until bubbly; may take up to a week). *Use yeast only to speed action.
Grated Potato Starter
2 raw potatoes grated in bottom of the Sourdough Pot.
1 yeast cake, diluted in
2 cups warm water
2 Tablespoons sugar.
Flour (enough to make a smooth, creamy batter)
Beat well. Get all lumps out at this time so it is not necessary to remove any flour lumps later when ready to use the Starter. Cover. Place Sourdough Pot on the shelf in a warm spot, free from drafts. This Starter takes longer to start working, but in a week it will be bubbling.
Don’t use up all the starter when you do some baking. To the starter which you reserve, add one cup flour and one cup warm water. Stir the starter daily. Try to replenish the starter about once a week.