Thoroughly whisk together 70 g plain flour with 120 ml water in a large bowl. Cover with a plate and set aside for 24 hours
Over the next three days, twice a day, add 70 g plain flour and 120 ml water to the sourdough starter, whisking well.
Once the starter is domed with bubbles on top, it is ready; you may need to feed the dough for another day if it is not yet ready.
Combine 850 g of the sourdough starter with the bread flour, salt, honey, and turmeric in the bowl of a stand mixer.
Fit the mixer with a paddle attachment and beat on a medium-low speed for 30 seconds. Start adding the remaining water, in four additions, until the dough comes together like a thick, sticky cake batter; continue to beat for 3 minutes.
Line a large mixing bowl with a sheet of parchment paper. Spray the paper with cooking spray and scrape the dough into it.
Cover with a greased piece of clingfilm and leave to rise in a warm place until doubled in size, 4-6 hours.
After rising, remove the clingfilm. Preheat the oven to 220°C (200° fan). Place a large baking tray in the oven to preheat.
After preheating, use the parchment paper in the bowl to lift the dough onto the preheated tray. Spritz the top of the dough with some water.
Bake until the bread is risen and golden-brown, 40-50 minutes. Remove from the oven and dust with flour, leaving the bread to cool on a wire rack before slicing and serving.
For 8 – 10 servings or for 1 loaf