Time to make the sponge! In this six-part series called “Follow the Sourdough,” Chef John shows you how to make sourdough bread, from beginning to end. Last time, you observed the tiny bubbles that told you your sourdough starter was alive and well, and almost ready for breadmaking duty. Today, you’re ready to roll! It’s time to use your sourdough starter to make the sponge. The key here is to use warm but not hot water. Hot water could wipe out the yeast you’ve been so carefully nurturing for the last few days. The timing here is key. See how it’s done. Want to see the previous episode? Check out How to Tell if Your Sourdough Starter Is Alive & Well. Ready for what’s next? Move on to How to Knead Your Sourdough Bread. Or start at the very beginning with How to Make San Francisco Sourdough Starter.