Day 1: Combine 113 grams (1 cup) organic all-purpose flour with 113 grams(½ cup) of room temperature water. Store this mixture in a one quart glass container. Cover the container loosely and let it sit at room temperature for 24 hours.
Day 2: Most likely, no activity will be occurring at this point. It is possible to see a bit of bubbling or growth. Regardless of the level of activity, we are now ready to do our first discard and feeding. Remove half of the starter, which is 113 grams or ½ cup. Feed the starter with 113 grams each of flour and lukewarm water. Stir it up, cover loosely and let it sit for another 24 hours.
Day 3: The starter may be showing a little life at this point: bubbling, growing and smelling a little funky. Now it is time to begin feeding the starter twice a day, ideally every 12 hours. Just like the previous days, half of the sourdough starter must be discarded and then 113 grams of flour and lukewarm water added back in. Stir and cover the starter. If the starter has not been growing or bubbling, repeat day 2.
Day 4: Weigh out 113 grams of starter and discard the rest. Feed the starter 113 grams each of water and flour. Place a rubber band around the vessel at the level of the starter. This will measure the growth activity of the starter and act as a gauge for the level of activity.
Day 5 & 6: Repeat the feeding and discarding for two more days. The starter will become very bubbly and have a fruity, acidic aroma. It will rise in the vessel after feeding, then gradually shrink down a bit when the activity slows and it needs to be fed again. Only use it for baking when it is at peak activity, nice and bubbly.
Once your starter is active, begin a maintenance schedule of feeding and discarding every twelve hours (ideally) when stored on at room temperature, or every week when stored in the refrigerator. The more you feed and discard, the faster it will consume the nutrients and grow! The fridge can help to keep it manageable when you aren't actively baking.