To check if starter is ready to be used, add a small piece of starter to a bowl of water. If it floats, the starter is active. This test is not always accurate.

Mix flours together with 375 ml of water, let rest 30 minutes - 2 hours for autolyse.

Add starter to dough and pinch into dough with hands.

Add 10g of salt and the remaining 25 ml of water, the dough should be a little easier to mix and very watery.

With force, slap dough onto un-floured surface and fold together 5 minutes until some strength develops and the dough can hold its form.

Lightly oil bowl or proofing box and add dough.

Proof dough in proofing oven set to 85 F or at room temperature.

With oiled hands, pick up dough at middle and fold onto itself, then rotate dough 90 degrees and fold again. Repeat every 30 minutes for 3-4 hours, total of 6-8 times.

Prepare a generously floured towel placed in shaping basket or bowl to hold the dough overnight.

Place dough on an un-floured surface and carefully form dough into a round shape. Lightly flour and let relax 10 minutes covered with a towel.

Rollover onto floured surface with un-floured bottom facing up, pull sides out and fold together like an envelope.

Stitch bottom together to hold and let rest seam-side down on counter to seal. Move into basket, seam-side up, and cover with flour, refrigerate overnight covered in towel.

Flour parchment paper, preheat dutch oven on middle rack of oven set to 500F.

Gently roll out dough onto parchment paper and score top of dough ball with a razor blade.

Transfer dough with parchment paper into hot Dutch oven. Bake for 15 minutes with the lid on and 30 minutes off, cook times vary.

Knock bottom of bread to hear hollow sound if bread is fully cooked.