In a medium size non-reactive bowl*, combine the 1 cup bread flour, ½ cup grated potato and 1 cup filtered water. Mix well, cover and set aside at room temperature (65°F ~ 75°F) for 24 hours.

After 24 hours, there may or may not be any bubbles in the mixture. Either way, discard (or give it to a friend to cultivate) all but ½ cup of the starter (4 ounces) and add 1 cup bread flour & 1 cup filtered water. Stir, cover and let rise at room temperature for 24 hours.

After 24 hours, you will see small bubbles forming with some fruity aroma and some evidence of expansion. Discard all but ½ cup (4 ounces) of the starter and stir in 1 cup of bread flour and 1 cup filtered water. Mix, cover and set aside for 12 hours. Again discard all but ½ cup (4 ounces) of the starter and stir in 1 cup of bread flour and 1 cup filtered water. Mix, cover and set aside for 12 hours. The sourdough starter is complete at this point. But if you want a pronounced sour flavor, then continue to feed the starter for another 2 times every 12 hours. After 4~5 days of consistent feeding, your levain should be ready to use in a sourdough bread. If not don't lose heart; keep feeding it regularly, and it will gain strength. Patience is a virtue here!!.

You will have about 1½ cups of sourdough starter at this point. Store it in a non-reactive jar either at room temperature (a serious sourdough baker) or in the fridge (occasional baker).

To feed your starter, remove it from the fridge and set aside for a few minutes to take the chill off. Stir it to make sure that the hooch is incorporated. Weigh 113 grams of the starter into a small ceramic or glass jar. Discard the remaining starter*. Add 113 grams each of all purpose flour and water. Stir well to combine. Cover loosely with a plastic wrap and place in a warm place.Place a rubber band on the jar to mark the top of the starter. Depending on how warm your house is, it will take about 4~6 hours for it to double in volume. Once it is bubbly and active, it is ready to be used. Or you can return it to the fridge.