First thing the following morning: begin with adding a couple of tablespoons of the leaven to the dough, squeezing, pushing your hand in and twisting. Once that is incorporated add more leaven, repeating the technique mentioned previously. Next add the salt and caraway, sprinkling evenly across the dough and again repeating the technique to incorporate. Repeat with the remaining leaven. You should have a fairly soft, sticky dough. Cover and leave to rest for 1 hour.
Once the dough has rested, have ready a round banneton basket ready, lined with a muslin cloth heavily dusted with rye flour. Dust the work surface with rye flour, then turn the dough out. Roll and shape into a round, ensuring the under side is smooth. Place the smooth side down in the banneton. Press down, then dust with rye flour. No need to cover.
Oven 235°C fan.
Prove for 90-120 minutes (depending on the temperature in your kitchen) or until cracks appear on the surface of the dough.
Pre-heat the oven for at least half an hour before baking the bread. If you have a cloche or casserole pot, put it in as you turn the oven on.
When you’re ready to bake, turn the dough out onto a piece of baking parchment. Dust with a little more rye flour and leave for 10–15 minutes to allow the dough to settle; you’ll notice a few cracks appearing. No scoring is required — the beauty of this bread lies in its natural cracks. Place it in the hot cloche or pot and bake for 35 minutes. Remove the lid and continue baking for a further 12–15 minutes. The crust should be very dark. Cool on a wire rack. The bad news is that the bread shouldn’t be sliced for 24 hours — the crumb needs time to set… sorry!