Combine 1 cup (113 grams) of whole wheat or rye flour with ½ cup (113 grams) of water thoroughly in the non-reactive container. Leave the container out at room temperature (at least 70 degrees), uncovered, for 24 hours.

Discard half the starter (about 113 grams or ½ cup of the mixture). To the remaining starter, add 1 cup (113 grams) all purpose flour and ½ cup (113 grams) water. Combine and let sit at room temperature for 24 hours.

You should notice some bubbles and will want to start feeding your starter every 12 hours now. Continue feeding by weighing out 113 grams starter, discarding the remainder, and feeding with 113 grams all purpose flour and 113 grams water. Mix, cover, and let rest for 12 hours before repeating again.

Repeat the same 1:1:1 ratio of starter, flour, and water feeding every 12 hours.

Once you have an active sourdough starter that has doubled in volume, you can begin to store it in your refrigerator covered and reduce the feedings to about once a week.

To maintain your sourdough starter, you should feed it at least once a week. Before you bake with it, you must revive your starter first by feeding it with fresh flour and water, leaving it out covered at room temperature.

Weigh out 113 grams or ½ cup of starter and discard the rest. To the remaining mixture, add 1 cup (113 grams) all purpose flour and ½ cup (113 grams water). Mix and let rest covered until the mixture has doubled.