1. Prepare Your Jar: Start with a clean glass jar or container. It’s helpful to have a jar that’s large enough to accommodate your starter as it grows after feeding, typically at least double its initial volume.

2. Measure Your Starter: Remove your desired amount of active sourdough starter from its current container. This is the “mother” starter you’ll be feeding. For example, if you’re aiming for a 1:1:1 ratio, you might take 50 grams of starter. Discard any excess starter, or use it for baking.

3. Add Flour: To your measured starter, add the appropriate amount of flour according to your chosen ratio. If you’re using a 1:1:1 ratio with 50 grams of starter, you would add 50 grams of flour.

4. Add Water: Next, add the corresponding amount of water. Following the 1:1:1 ratio example, you would add 50 grams of water. Always add water gradually if you’re unsure, as different flours absorb water differently.

5. Mix Thoroughly: Using a spoon or spatula, mix the starter, flour, and water until no dry pockets of flour remain. The mixture should be smooth and consistent, resembling a thick batter. Scrape down the sides of the jar to keep it tidy.

6. Mark the Level: Place a rubber band or use a marker on the outside of the jar to indicate the initial level of your freshly fed starter. This will help you visually track its rise and fall, indicating its activity.

7. Cover Loosely: Cover the jar loosely with a lid or plastic wrap. This allows air circulation while preventing the starter from drying out. Do not seal it tightly.

8. Allow to Ferment: Leave your fed starter at room temperature to ferment until it doubles or triples in size and shows plenty of bubbles, indicating it’s active and ready to use. This typically happens within 4-12 hours, depending on the ratio and temperature.