For the preferment:
50g ripe rye-wheat starter
90g light rye
90g room temp water

For the final dough:
230g perferment
320g strong white
65g wholemeal
180g room temp water
2 tsp salt

Prepare the preferment the night before:
mix 90g water into the starter in a medium-sized bowl. Add the light rye and mix until even consistency.
Cover the bowl and leave at room temp overnight.

Prepare the final dough:
Pour 180g water into the bowl of preferment and mix to an even consistency.
Measure out the flours and salt into your mixing bowl and dry-stir to ensure salt is evenly mixed in.
Pour the liquid preferment mixture over the dry ingredients and roughly combine with your hand(s).
You only need to get the dough barely combined at this stage, this loaf uses a minimal kneading technique.
Cover the bowl and leave for 10 mins.
Lightly oil the work-surface, scoop the dough out of the bowl and onto the surface.
Perform a quick knead (about 15 secs) then leave the dough sat while you clean out the mixing bowl.
Very lightly oil the mixing bowl and return the dough to it, leaving it covered for a further 10 mins to rest.
Perform another short knead, then leave for 30 mins.
Perform a further short knead, then leave for 1 hr.
Perform a quick knead and now shape the loaf, according to the style of proving basket you have.
Leave to prove for 3 hours (or 2 if it's summer) before baking.
Preheat your oven to Gas 9 (approx 250 C) with a baking stone inside. Also place a heavy-bottomed pan
in the bottom, which will be used to provide the steam.
Bake the loaf on the stone at max temp for 20 mins - pour in a cup of boiling water into the lower pan
1 min after the loaf goes in.
Turn the heat down to Gas 6 or 7 (approx 220 C) for a final 10 mins.
Always consider you may want to rotate the loaf as it cooks, to account for any heat imbalance in your oven.

Credit to Dan Lepard for the quick knead technique, see https://www.danlepard.com