Preparation Instructions

1. Boil the potatoes until soft, then rice or finely mash. Measure out 1 1/3 cups of potatoes.
2. In a medium bowl, combine the yeast with the warm water and 1/2 cup of the flour. Cover and let stand for about 25 minutes, until the mixture is frothy.
3. With an electric mixer, beat the yeast mixture with the mashed potatoes, 3 tablespoons of the olive oil, 2 teaspoons of salt and the remaining 3 cups of flour at medium speed for 2 minutes. Knead for 5 minutes. Transfer to a lightly oiled bowl; turn to coat. Let stand covered for about 1 hour.
4. In a skillet, cook the leeks with the thyme, salt and sugar in the olive oil over moderate heat, stirring, until caramelized.
5. Transfer the dough to an oiled baking sheet and press to form a rectangle. Lightly brush the dough with olive oil; let stand for about 35 minutes.
6. Preheat the oven to 425°. Using your fingers, make indentations all over the dough surface. Top with the leeks, cheese, sea salt.
7. Bake the focaccia for 20 minutes, until the crust is golden brown. Let stand for 30 minutes to cool slightly. Slice into squares and serve.