Sundried Tomato and Olive Sourdough Ciabatta

1. In a large mixing bowl, combine the bread flour, all-purpose flour, salt, and sugar. 2. In a separate bowl, mix the sourdough starter with the water until well combined. 3. Gradually add the wet mixture to the dry ingredients, stirring until a shaggy dough forms. 4. Knead the dough on a lightly floured surface for about 10 minutes until smooth and elastic. 5. Add the chopped sundried tomatoes and olives to the dough, and continue to knead until they are evenly distributed. 6. Place the dough in a lightly oiled bowl, cover with a damp cloth, and let it rise at room temperature for about 4-6 hours, or until doubled in size. 7. After the first rise, gently stretch and fold the dough in the bowl to strengthen the structure. Cover and let it rest for another hour. 8. Line a baking tray with parchment paper. Gently transfer the dough onto the tray, being careful not to deflate it too much. Shape it into a rectangle about 1-inch thick. 9. Cover the shaped dough with a damp cloth and let it rise for an additional 1-2 hours, until puffed. 10. Preheat your oven to 220°C (425°F) and place a baking stone or an inverted baking tray inside to heat. 11. Once the dough has risen, carefully transfer it onto the preheated baking stone or tray. Bake for 25-30 minutes or until the ciabatta has a golden-brown crust and sounds hollow when tapped on the bottom. 12. Remove from the oven and let it cool on a wire rack before slicing.