Cook a medium-sized potato in 1 quart of water.
Mash fine and add enough water to make 3 pints.
Put into a quart jar.
Dissolve 2 packages of any quick yeast in 1/2 cup of lukewarm water.
Add to the jar with 2 tsp sugar and 1/4 tsp salt.
Soon it will start to work and foam.
Use two cups of this starter and follow your favorite recipe, deducting 2 cups of water from the recipe for the water used in the starter.
The remaining starter in the jar should be covered and put in a cool place or refrigerated to be used the next time.
Next baking, add warm potato water, sugar and salt and proceed as before. Always keep the jar in a pan of good warm water while it is working.
A half package of yeast may be added every month or so, but it may be used for many months without.