1. Gather Your Tools and Ingredients: Make sure you have your existing sourdough starter, your chosen flour, and filtered water ready. You’ll also need a clean jar or container for your starter, a kitchen scale for accurate measurements, and a spoon or spatula for mixing.

2. Weigh Your Existing Starter: Place your clean jar on the kitchen scale and zero it out. Add your existing sourdough starter to the jar. For a typical feed, you might aim for 50 grams (about 1/4 cup) of starter. This is the “1” in your 1:1:1 ratio.

3. Add Fresh Flour: Zero out your scale again. Add the same weight of fresh flour as your starter. So, if you used 50 grams of starter, add 50 grams of flour. Gently tap the jar or use your spoon to level the flour.

4. Incorporate Filtered Water: Zero out the scale one last time. Add the same weight of filtered water. If you used 50 grams of starter and 50 grams of flour, add 50 grams of water. The mixture will look a bit thick at first.

5. Mix Thoroughly: Using your spoon or spatula, mix all the ingredients together until there are no dry pockets of flour remaining and the mixture is smooth and uniform. Scrape down the sides of the jar to keep it tidy. The consistency should be like a thick pancake batter.

6. Mark and Store: Place a rubber band or use a marker to indicate the current level of your freshly fed starter on the outside of the jar. This will help you visually track its rise and fall. Loosely cover the jar with a lid (don’t seal it tightly, as gases need to escape) and place it in a warm spot (70-75 F or 21-24 C) to ferment.

7. Observe for Activity: Over the next 4-12 hours, watch for signs of activity. Your starter should begin to rise, developing bubbles on the surface and throughout the mixture. It will typically double in size or more, reaching its peak activity before slowly falling back down. When it’s at its peak, it’s ready to use for baking.