Directions
Step 1
In the bowl of a stand mixer fitted with the paddle attachment, mix the yeast, water, and honey for a few seconds. Turn off the mixer and allow the yeast to bloom (get foamy), about 5 to 8 minutes.
Step 2
Add 2 tablespoons olive oil, the fine salt, and flour and mix until a sticky dough forms. Switch to the dough hook and knead until smooth and elastic, about 7 minutes. The dough will still be somewhat sticky but should pull away from the sides of the bowl as you lift it. If it’s too sticky to handle, add more flour, 1 tablespoon at a time.
Note: If you don’t have a stand mixer with a dough hook, bloom the yeast, water, and honey in a large bowl. Add the olive oil and salt and then the flour, mixing with a large spatula and then with your hands. Turn the dough out on a lightly floured countertop, flour your hands, and knead until smooth, about 7 minutes.
Step 3
Pour 1 tablespoon olive oil into a clean, large bowl. With lightly floured hands, form the dough into a ball and roll it in the olive oil. Place the bowl in a warm spot in your kitchen and cover with a clean dish towel. Let rise until doubled in volume, about an hour. (If you poke it with a fingertip, it should spring back right away.)
Step 4
Pour 3 tablespoons olive oil into a 13×9 metal cake pan and rotate the pan to coat it well. Punch down the dough and turn it into the pan. Use your fingertips to press it out to the edges and into the corners of the pan. Use your fingertips or knuckles to make a pattern of indentations in the dough. Cover the pan with your kitchen towel and let it rest for 20 minutes while you preheat the oven
to 450°F.
Step 5
Use the fine slicing blade of your food processor or a mandoline to very thinly slice the potatoes. Toss in a bowl with 1 tablespoon olive oil and the rosemary.
Step 6
When the dough has risen and is ready to bake, go over the indentations if needed. Arrange the potato slices over the top, drizzle on the final 2 tablespoons olive oil, and sprinkle on the rosemary and coarse salt. Bake for 25 minutes, rotating the pan halfway through, until the focaccia is golden and pulls away from the sides of the pan and the potatoes are tender. Let cool for 5 minutes before serving.