Peel and dice the potatoes; cook them in boiling water for 20-25 minutes or until tender;
Let the potatoes cool down a little and then mash or rice them for a more uniform texture;
Dissolve the yeast in 10 tablespoons (150ml) of lukewarm water and add the sugar to active it;
Sift the two types of flour together; add the salt and the mashed potatoes;
Mix it all with a stand mixer, like a KitchenAid, fitted with a dough-hook attachment or by hand on a flat surface. Mix it until smooth and even;
Pour in the water along with the yeast and knead it carefully;
Gradually add 2 tablespoons of oil, one at a time;
Knead it with your hands or in a stand mixer at medium speed; don’t worry if the dough doesn’t come together, it will after you pour in some more water;
Pour in the water until it’s a soft and almost sticky mixture;
Knead it a couple of minutes until it becomes stretchy; the dough should release easily from the side of the bowl and twist around the hook; just don’t knead it too long;
Pour it onto a floured surface and sprinkle the dough and your hands with all-purpose flour; shape the dough into a rectangle and then fold the two sides into the center and then fold it again laterally;
When a smooth dough has formed, make a ball with floured hands and place it in the oiled bowl;
Cover the bowl with plastic wrap and let it rise until the dough has tripled in volume;
In the meantime, halve the tomatoes and dress them with salt, oil, and oregano; set them aside; a little liquid will be released;
Put the dough into an oiled round 10-inch (26-28cm) pan; flatten it with the tips of your well-oiled fingers;
Place the tomatoes and black olives spaced evenly on the surface and press them into the dough. Pour a little tomato liquid for a more flavorful taste;
Generously season it with extra virgin olive oil, dry oregano, and coarse salt;
Let the flatbread rise for one hour or until it has doubled in volume; the tomatoes and olives will have sunk into the dough;
Pre-heat the static oven to 400°F (200°C) and bake for about 25 minutes: first place the tray onto the lower rack for 10 minutes; then move it to the middle for the remaining 15 minutes;
Check for doneness: the edge should be crunchy- take it out of the oven and let cool down a bit before serving. This scrumptious flatbread is ready to be eaten either hot or cold.