After the last step, I fed the starter again: 100 grams starter, 100 grams tap water (the starter was fermenting easily enough, so I switched), 100 grams unbleached bread flour. Here's what the starter looked like before feeding: Starter after the fifth feeding
As soon as I post this I'm going to mix a levain (sponge) from the starter and let it ferment overnight; tomorrow I'll post the recipe for the easiest focaccia you'll ever bake.
100 grams active, bubbly sourdough starter
100 grams room temperature tap water
100 grams unbleached bread flour
Stir the ingredients together in a medium bowl and cover with plastic wrap. Let the levain ferment until well risen, about 8 to 12 hours.
I'll post the rest first thing in the morning in case you're going to make the sponge tonight.