For the poolish (long pre-dough) put all the ingredients in a bowl and stir well, cover with cling film and leave to stand overnight (approx. 12 hours) at room temperature.
Mix the flours together for the final batter. Halve the chilli pepper, remove the seeds and finely chop the chilli. Drain the peppers and cut them into small pieces. Mash the potatoes.
Add all ingredients, including poolish, to the flours and knead everything together well. Cover the dough and let rise for 1½ hours.
Place the dough on the well-floured work surface and divide it into 3 parts, then shape each into a bread and place on the baking tray, cover and let rise for another 1 ½ hours.
Preheat the oven to 220 degrees in good time, pour the bread in well and bake for about 35 minutes, possibly reduce the temperature to 200 degrees if the bread turns dark too quickly.
Tip: If you want it a little hotter, you can of course add more chilli to your bread.