For the pre-dough, dissolve 5 g yeast in 200 ml lukewarm water. Put 350 g flour (type 405) into a mixing bowl. Add yeast water. Knead with the kneading hooks of the mixer at medium speed for 2-3 minutes (see
Figure 1). Cover and leave to rise for 15-18 hours at room temperature (approx. 20°C) in a place protected from draughts.
Dissolve 10 g yeast in 350 ml lukewarm water. Put 450 g flour (type 550) into a mixing bowl. Add pre-dough, yeast water, oil and 2 teaspoons salt. Knead with the dough hooks of the mixer on medium speed for about 5 minutes.
Cut the dough in half. Coarsely chop the olives and knead them with floured hands under one half of the dough. Cover both halves of the dough in a bowl and leave to rise for about 1 1/2 hours.
In the meantime, line two baking trays with baking paper. Dust the work surface generously with flour. Form both doughs one after the other on the work surface loosely into 1 loaf of bread each (approx. 50 cm long).
Cut in half with the dough card. Place 2 loaves of bread on each baking tray. Cover with a tea towel (see fig. 3) and leave to rise for about 45 minutes.
Preheat oven (electric cooker: 225°C/circulating air: 200°C/gas: level 4). Dust the breads with flour. Bake them one after the other in a hot oven for 15-20 minutes until light brown. (If the breads sound hollow when you knock on the bottom, they are ready). Remove the ciabattas and let them cool down.