Makes 2 (9-inch) round pans or 1 baking sheet.
Note: This recipe is based on "My Bread" by Jim Lahey (Norton, $29.95). Lahey reinvigorated the ancient method of giving dough plenty of time to rise, spurring the no-knead bread trend and taking the fear out of yeast. Focaccia is best eaten within hours of baking.
• 1 russet or Yukon gold potato, to measure 1 cup when peeled and cut in small chunks
• 21/2 c. cool water
• 4 c. bread flour
• 21/2 tsp. instant yeast
• 1 tsp. sugar
• 3/4 tsp. salt
• 1 tbsp., plus 1/4 c. extra virgin olive oil, divided
• Toppings: Choose among fresh herbs, peppadew piquanté peppers, roasted cherry tomatoes, caramelized onions, pitted olives, etc.
• Coarse salt, to taste
Combine potatoes and water in a small saucepan, cover and bring to a boil. Cook until the potato chunks fall apart when pierced with a fork.
Blend water and potatoes until smooth, then put aside to cool to about 120 degrees, which is still very warm, but not hot. (Take care when whirring hot liquids in a blender; they can "erupt.") Or strain out potatoes, mash, then recombine with the water.
In a large bowl, whisk together flour, yeast, sugar and salt. Add the cooled potato purée and mix until you have a wet, sticky dough. This takes only about 30 seconds. Cover the bowl with plastic wrap and let it sit undisturbed until the dough triples in size, about 2 to 3 hours.
Lightly oil a rimmed baking sheet, or 2 (9- to 10-inch) round pans with 1 tablespoon olive oil. Scrape the dough into the pan. Dipping your fingers in remaining 1/4 cup olive oil, use your hands to gently pull and press dough to the pan edges. Drizzle remaining oil and use your fingertips to press down all over the dough to create dimples on the surface.
If desired, press toppings well into the dough in an attractive pattern.
Preheat oven to 400 degrees.
Let the dough rise in a warm, draft-free spot until it reaches the edges of the pan, about 45 minutes. Sprinkle with coarse salt, to taste.
Bake on center rack of oven for 30 to 45 minutes until golden brown. Remove pan from oven and let it rest a few minutes on a wire rack before removing the focaccia from the pan. Serve warm or at room temperature.