Add the water to the biga bowl and then add the yeast. Wait for 10 minutes to let the yeast dissolve and then squish the biga/water mixture together with your hands to make a milky paste.
Add the fresh flour and the salt. Squish it all together well to get the lumps out. Leave it for 30 minutes to let the dough relax.
Add the potato and the beets and gently stretch and fold the dough around them gently so you don't squash the beets to death. Lumps of mash are ok too.
Cover the dough and leave it for 30 minutes.
Stretch and fold the dough and then let it rest for 30 minutes.
Repeat this four times - for a total of two hours.
Meanwhile prepare two baking trays by lining them with non stick parchment.
Scrape the dough out onto a lightly floured surface and divide it into four equal pieces.
Put a sprinkle of flour on your counter and, one by one, pick up a blob of dough and place it in front of you on the floury surface. Sprinkle flour on top of the dough as well. Squeeze the dough gently to elongate it so that it is about 25 cm long. As you squeeze you will hear air bubbles popping. Pick your dough up and place it on a baking tray. Repeat this with all the blobs of dough, placing two ciabattas on each baking tray.
Cover and let rest for 30 minutes.
Preheat the oven to 230 degrees C and pop the dough in. Bake for 20 minutes and then remove and let cool completely on a cooling rack.