• Boil the potatoes and peel them, then let them cool. Once they're cool enough, mash them well. You can use a potato ricer. Do not use a blender or a mixer. The potato will become sticky and will ruin the consistency of the focaccia.
• Mix the two flours in a bowl
• If you use fresh yeast, dissolve it into the water a few minutes before starting.

Using a kitchen machine

• In the bowl of the mixer put the water and the yeast (or add the sourdough instead). Add the flour mix and start at the lowest speed and mix well.
• Add the potatoes and increase the speed of the mixer. Let the machine mix the dough for 5 minutes then add three tablespoons of oil and a large pinch of salt. If the dough is too soft, add a little more flour. Continue kneading the dough for another 2 minutes and then let it rise for until doubled in size in a warm place.

By hand

• In a bowl mix the water with the yeast (or sourdough). Start adding the flour a little at a time, mixing it with a spatula or with your hands. Let the dough sit for 30/40 minutes. This will reduce the kneading time.
• Add the mashed potatoes and salt and keep knead until the potatoes are incorporated into the dough.
• Add the oil and knead to incorporate. then let it sit in a warm place until doubled in size.

Cooking the focaccia

• Preheat the oven at 240°C (440°F). Grease a baking tray ( about 28cm diameter) with some oil and then spread the fermented dough onto it. Wash the cherry tomatoes and cut them in half. Push them into the dough. Add a drizzle of oil on the surface. Sprinkle origano and a little bit more salt and put it in the oven.
• When the oven is hot, cook for 5 minutes at 240° then reduce the temperature to 180° C (390°F) and cook for about 30 minutes. When the focaccia is golden brown it’s ready to be served.