Levain is kind of just a fancy word for a larger starter. Or a “pre-ferment”.
The idea is: you keep the starter alive with a minimal amount of flour, and then when you’re ready to bake, you build a larger starter, which will be used in your loaves.
If you already have a sourdough bread recipe you follow, there should be instructions for building your levain within that recipe.
This will be done around 12-15 hours before you intend to make your dough. It should double in size and be nice and active/bubbly.
This is how I build my levain:
27g starter
135g water
135g flour
This will give you 270g of leaven to build your dough around.
Simply add all the ingredients into a jar, and stir. It should be the consistency of a thick pancake batter.
Then place a marker onto the jar so you know the level at which the starter started in the jar (washable marker or an elastic band works great!). And then leave the jar out on your counter.
Once your Levain had doubled or tripled, it’s ready for you to build your dough.
