1) Add 60g (1⁄4 cup) lukewarm water to the starter container, and stir to partially dissolve the starter and loosen it from the container.
2) Place the starter / water mixture into a bowl. Add 230g (1 cup) lukewarm water and 240g (2 cups) of all-purpose flour. Mix, cover the bowl loosely, and let sit at cool room temperature (68 to 80°F) for 8 to 12 hours. The starter should expand and start to become bubbly.
3) Stir the starter and measure out 110g (1⁄2 cup) to feed. The remaining starter can be thrown away or used in recipes calling for sourdough discard. To the 110g (1⁄2 cup), add 110g (1⁄2 cup) water and 110g (1 cup) flour. Stir well, cover, and let sit until the starter bubbles and increases in volume, about 6 to 8 hours.
4) Repeat feeding process from Step 3 until the starter is bubbly and almost doubled. If you don’t plan on baking with it right away, cover it and put it in the refrigerator.