Cut a potato into bite-size. Heat the potato in a microwave at 600W for 1.5 to 2 minutes until softened. Mush it and let it cool; set aside.

Put lukewarm water (35℃ / 95 F) in a bowl of a stand mixer, add instant dry yeast and cane sugar, and stir well. I used KitchenAid Artisan 3.3L for a stand mixer. Add the bread flour and durum wheat semolina, and mix roughly with a spatula.

Add salt and olive oil, and mix roughly. Add the mashed potatoes, and mix roughly.

Knead it for 2 minutes at speed 2. Then knead for 5-6 minutes at speed 4. Remove the dough from the hook, and turn it over. Knead again for 5-6 minutes at speed 4 until smooth.

Put the dough onto a work surface. Use your hand to bang down the dough against the work surface 100-150 times. Stretch gently one part of the dough thinly. It's ready if it doesn't tear.

Shape it into a ball while stretching the surface and put it in a lightly oiled bowl. The surface should be smooth and elastic. Cover it with cling wrap and let it rise at 35℃ / 95 F (or a warm place) for 60-90 minutes until doubled in size. Finger Dent Test! Press your floured finger into the dough. It's ready if the dent springs back a little and it stays without filling in.

Press it gently to remove the air. Divide it into four equals.

Punch down each, and shape it into a ball while stretching the surface. Cover them with a tightly wrung wet cloth and leave for 15 minutes.

Punch down each, and use a rolling pin to roll out into a circle, 1 cm / 0.4-inch thick. Transfer them to a parchment-lined baking sheet. Gently brush the top with olive oil.

Let it rise at 35℃ / 95 F (or a warm place) for about 30 minutes until 1.3 times in size. Preheat the oven to 230℃ / 446 F.
Use your olive-oiled finger to poke deep dents all over the surface. Poke down deeply until you touch the baking sheet. Brush the surface with olive oil again, and fill the dents with the oil.

Sprinkle evenly with dry rosemary leaves and sea salt. Lower the oven to 210℃ / 410 F and bake for 18 minutes until golden brown.