Why our sourdough takes two days

Every country sourdough you buy on Tuesday was started on Sunday night (sample).
The starter is fed in the evening, the dough is mixed the next afternoon and then rests in the fridge overnight. The cold slows the yeast down and gives the bacteria time to make the flavour.
At six the loaves go into the stone oven at 250°C with a tray of water for steam. That is where the dark, crackly crust comes from.