Mix the levain ingredients and let stand at warm room temperature (23-24˚C) for 8-12 hours. Look for a 25-50% increase in volume. When ready, it should have a fruity tangy smell and taste. A younger levain will yield a more mild flavour in the final loaf and a longer fermented levain will result in a more sour loaf.
Autolyze: One hour before the final mix, combine the flour and water (no salt) of the final dough until fully incorporated with no dry bits left. Cover the dough and allow to rest.
Final mix: Add the levain and salt and hand mix to incorporate.
Development: Use the ‘slap and fold’ technique to develop the gluten in the dough. 5-6 minutes.
Bulk Fermentation: Ferment for 3-4 hours at warm room temperature (23-24˚C) with two folds at 45 and 90 minutes, or three folds at 30, 60 and 90 minutes if the dough seems very loose.
Divide the dough into two 750 g pieces and preshape. Bench rest for 20 minutes. Shape the loaf into either a Boule or Batard depending on the shape of your proofing basket.
Final proof: Proof approximately 2 hours (use the finger dent test). You can also proof for 1 hour and then retard in the fridge for 8-36 hours.
Turn the dough out onto a piece of parchment, score and place in the dutch oven preheated to 500˚F with the lid on. Reduce the oven temperature to 460˚F. Remove the lid after 20 minutes and continue baking 10-20 minutes until deep brown. A fully cooked loaf will have an internal temperature of 210˚F.
Cool the loaf fully before cutting (at least one hour). If the loaf is cut while it is still hot, it may end up with a gummy interior.