Flat bread with potatoes and sage
Put potatoes and water in a casserole, cover and boil until they are soft. Blend potatoes with their cooking water until you obtain mashed potatoes. Let it warm until about 50°.
Dissolve the sourdough in 250g of water, then add the flour with the sugar, 3g of salt, 25g of olive oil and mashed potatoes, the minced sage and the rest of the water in a bowl. Mix quickly and let it rest 5-6 hours or until the volume of the dough has doubled. Roll the dough on a pan of about 30 x 40 cm with some oil or oven paper using a paddle and some flour. Put the rest of the salt and the rest of the oil. Let it rest for 2 or 3 hours more until the volume doubles. Cook in the oven at 200°C for 30-40 minutes (move the dough gently because it is delicate). Remove from the oven and taste it when it is lukewarm.
You can find this recipe here: http://vanigliacooking.blogspot.it/