To thin out a sourdough starter, you can adjust its hydration level by adding more water. Here's a step-by-step guide:
Take your existing sourdough starter and transfer it to a clean container.
Determine the desired hydration level. A higher hydration level means a thinner consistency, while a lower hydration level means a thicker consistency. For example, if your starter is currently at 100% hydration (equal parts flour and water by weight), and you want to thin it out to 150% hydration, you'll need to add more water.
Weigh your starter. This will help you calculate the amount of water to add accurately. For example, if you have 100 grams of starter at 100% hydration, you'll have 50 grams of flour and 50 grams of water.
Calculate the amount of water needed. Multiply the weight of your starter (excluding the weight of the water) by the desired hydration factor and subtract the weight of the flour. For example, if you want to achieve 150% hydration with 100 grams of starter and 50 grams of flour, you'll multiply 100 grams by 1.5 (150%) and subtract 50 grams of flour. The result is 100 grams of water needed.
Add the calculated amount of water to your starter. Pour the water into the container with the starter and mix well until fully incorporated.
Optional: If necessary, adjust the total amount of starter by discarding or adding more flour and water. This will ensure you have the desired amount of starter for your baking needs.
Allow the thinned-out starter to sit at room temperature for a few hours or until it becomes active and bubbles appear. This may take longer than usual due to the increased hydration.
By following these steps, you can adjust the hydration level of your sourdough starter to achieve the desired consistency.