Place the sourdough, 180mls water and the flours into a stand mixing bowl

Mix on a low speed using a dough hook until a dough forms

Cover and leave to rest in a warm place for 30 minutes

Add the rest of the water and salt and mix on low for 10 minutes

Cover and leave to rest in a warm place for 1 hour

Knead for 10 minutes using the dough hook on a low speed

Cover and leave to rest in a warm place for 40 minutes

Knead for 10 minutes using the dough hook on a low speed

Cover and leave to rest in a warm place for 1 hour

Turn onto a surface generously dusted with flour

Dust the top with flour and shape into a round loaf using a pastry scraper

Place seam side down onto a lined baking tray

Score the top a few times and cover with a dry dish towel

Set aside to prove in a warm place for 1 hour

Preheat the oven to 220° Celsius

Place the baking tray into the oven with a handful of ice cubes

Bake for 40 minutes and remove from the oven

Set aside to cool on a wire rack before slicing