Directions

1. In a mixing bowl, combine the dark rye flour, bread flour, cocoa powder, and caraway seeds. Mix all the dry ingredients together, then add the water and mix until the dough starts to come together.
2. Cover the bowl with a tea towel and let it rest for 1 hour to hydrate the flours.
3. Add the ripe starter and, using a damp hand, fold it through the dough. Once the starter is almost completely absorbed, add the salt and continue to mix for another 2-3 minutes, ensuring you can't feel any salt granules.
4. Scrape down the edges of the bowl to clean it, then cover with the tea towel and let rest for 30 minutes.
5. After 30 minutes, stretch and fold the dough by pinching one corner, pulling it up and folding it over itself. Repeat this three more times until you've done four stretches and folds in total.
6. Cover with the tea towel and let it rest for another 30 minutes. Repeat the same stretch and fold technique from the previous step. Do this two more times for a total of four rounds over two hours.
7. After the last round, the dough should be smooth and elastic. If not, continue with one to two more rounds as needed.
8. After the last round, cover with the tea towel and leave to bulk ferment at room temperature until the dough has grown by 40%. This can take 2-5 hours depending on your kitchen's temperature. At 24°C (75°F), it took 2.5 hours.
9. Once bulk fermentation is complete, turn the dough out onto a floured surface using the 50/50 rice flour and bread flour mix.
10. Cut the dough into two even pieces and preform your loaves by pulling the edges in tightly to form a loose ball. Cover with a tea towel and rest for 35-40 minutes.
11. Liberally dust your oval bannetons. Shape each loaf by flattening it out first into an almost triangle shape, with the piece closest to you narrower than the piece further away. Fold the left and right sides of the dough in, then roll from the top towards yourself, pressing firmly every 3-4 cm. Crimp the seam well, then place the shaped loaf into the banneton, seam facing up.
12. Dust the loaves with more of the rice flour mixture, place them into an airtight bag, and refrigerate overnight to cold ferment.
13. The next day, preheat your oven or pizza oven to 280-300°C (536-572°F). Remove the dough from the fridge 20 minutes before baking. Turn out the dough onto a peel, score the top using a razor blade, dust off any excess flour, and place into the oven. Steam for the first 5 minutes of the bake, then continue baking for another 30 minutes or until fully cooked and the desired colour is achieved.
14. Let the bread cool completely before slicing. Enjoy your rye sourdough!