- Dissolve starter and salt into the water.
- Combine the white and rye flours and add to water, mix until flour has been incorporated.
- Leave for an hour and then fold - Fold the edge of the dough into the centre. Work your way around the outside. Do this 10-15 times until the whole thing have been folded in on itself.
- Leave for anywhere between 5-10 hours depending on how warm your house is. Repeat the folding process another 2-3 times during this time. At the end, the dough should be quite puffy.
- Pre-shape into a ball and leave for an hour.
- Shape and transfer into a proving basket.
- Leave in the fridge, uncovered for anywhere between 8-48 hours (whenever you’re ready to bake).
- Put a heavy, cast iron casserole dish (with a lid) into the oven at 245c for at least 30 minutes.
- Take dough from the fridge about 30 minutes before baking, remove dough from the basket, dust off excess flour and score.
- Put the dough into the dish without burning your hands, stray some water in and put the lid on.
- Bake for 35 minutes, remove the lid and continue to bake for another 10-20 minutes.
- Remove, set on baking tray and leave for at least an hour too cool down before cracking into it.