Ingredients:

Preparation:

For the dough 1. Boil 1 quart water in small saucepan; add potato and simmer until tender, about 25 minutes. Drain potato well; cool until it can be handled comfortably and put through fine disk on ricer or grate through large holes on box grater. Reserve 1 1/3 cups lightly packed potato. 2. Meanwhile, in large bowl of electric mixer or workbowl of food processor fitted with steel blade, mix or pulse yeast, 1/2 cup flour, and 1/2 cup warm water until combined. Cover tightly with plastic wrap (or put workbowl lid on) and set aside until bubbly, about 20 minutes. Add remaining dough ingredients, including reserved potato. If using mixer, fit with paddle attachment and mix on low speed (number 2 on KitchenAid) until dough comes together. Switch to dough hook attachment and increase speed to medium (number 4 on KitchenAid); continue kneading until dough is smooth and elastic, about 5 minutes. For food processor, process until dough is smooth and elastic, about 40 seconds. 3. Transfer dough to lightly oiled bowl, turn to coat with oil, and cover tightly with plastic wrap. Let rise in warm, draft-free area until dough is puffy and doubled in volume, about 1 hour. 4. With wet hands (to prevent sticking) press dough flat into generously oiled 15 1/2-by-10 1/2-inch jelly-roll pan. Or, halve and flatten each piece of dough into 8-inch round on large (at least 18 inches long), generously oiled baking sheet. Cover dough with lightly greased or oil-sprayed plastic wrap; let rise in warm, draft-free area until dough is puffy and doubled in volume, 45 minutes to 1 hour. 5. Meanwhile, adjust oven rack to lower-middle position and heat oven to 425 degrees. With two wet fingers, dimple risen dough at regular intervals. For the topping 6. Drizzle dough with oil and sprinkle evenly with rosemary and coarse salt, landing some in pools of oil. 7. Bake until focaccia bottom(s) are golden brown and crisp, 23 to 25 minutes. Transfer to wire rack to cool slightly. Cut rectangular focaccia into squares or round focaccia into wedges; serve warm. (Focaccia can be kept on counter for several hours and reheated just before serving. Or, wrap cooled focaccia in plastic and then foil and freeze for up to 1 month; unwrap and defrost in 325-degree oven until soft, about 15 minutes.) HAND-KNEADED FOCACCIA Follow Master Recipe for Rosemary Focaccia, through step 1. In step 2, mix starter ingredients with wooden spoon in large bowl; cover and let stand 20 minutes. Add 1 1/2 cups flour to starter, then beat with wooden spoon for 5 minutes. Add 1 1/4 cups flour along with remaining dough ingredients; continue beating until dough comes together. Turn dough onto floured surface; knead in remaining 1/4 cup flour until dough is elastic and sticky. 4 to 5 minutes. Transfer dough to oiled bowl as in step 3 and follow remaining instructions. SAGE FOCACCIA Follow Master Recipe for Rosemary Focaccia, adding 1 tablespoon chopped fresh sage leaves with other dough ingredients in step 2 and substituting 24 whole fresh sage leaves (one per oil-filled dimple) for rosemary. PARMESAN FOCACCIA Follow Master Recipe for Rosemary Focaccia, substituting 2/3 cup grated Parmesan cheese for rosemary and coarse sea salt. FOCACCIA WITH BLACK OLIVES AND THYME Follow Master Recipe for Rosemary Focaccia, substituting 1 teaspoon fresh thyme leaves and 24 pitted large black olives (one per oil-filled dimple) for rosemary. Notes: Makes one 15 1/2 by 10 1/2-inch rectangle or two 8-inch rounds Rapid-rise yeast reduces the preparation time by more than an hour. If you use an equal amount of regular active dry yeast instead, let the sponge in step 2 develop for thirty minutes rather than twenty, and increase the first and second rises to one and one-half hours each.