Scrub the potato and add it to a small pot filled with water. Boil until the potato is soft when pierced with a knife, about 30 minutes. Drain, cool, and peel.
1 small Yukon gold potato
Use a tiny amount of olive oil to grease a medium to large sized mixing bowl and set aside.
¼ cup extra virgin olive oil
Combine the bread flour, yeast, black pepper, two of the three teaspoons of salt, and pinch of sugar in a mixing bowl.
4½ cups (562 grams) bread flour, 2¼ teaspoons (1 packet) instant dry yeast, 2 teaspoons ground black pepper, 1 tablespoon kosher salt, 1 pinch granulated sugar
Add the potato to the mixing bowl with a potato ricer or mash by hand in a separate bowl and add. Mix together.
Add the water to the mixing bowl and knead with the dough hook for about 7 minutes on a medium speed, scraping the wet, sticky dough down a few times with a silicone spatula to ensure even mixing. You can mix by hand but know that it's a stiff arm workout!
1¾ cups (400 grams) warm water
Turn the focaccia dough into the greased bowl and let rise until doubled in volume, about one and a half to two hours.
Meanwhile, line a 9 by 13 inch pan with parchment paper (using binder clips to secure the parchment in place if you like) and drizzle with one tablespoon of the olive oil.
Scrape the dough into the prepared pan. Then, dip your fingers into the olive oil drizzled in the pan and push the focaccia dough evenly into the pan.
Cover with plastic wrap and let it rise in a warm place until doubled in size, about one to one and a half hours.
When about ready to bake, preheat the oven to 425℉.
Drizzle the remaining olive oil over top of the focaccia - you may need a little more or little less than the remaining three tablespoons, but you want to cover it completely. Sprinkle the remaining teaspoon of salt across the top, and use your fingers to make little dimples.
Bake for 30 minutes in the middle of the oven until the focaccia is a golden brown. Serve immediately if serving as a dip or with cheese, or let cool completely for sandwiches.