1. In the bowl of an electric mixer, combine 1/4 cup water and yeast. Let stand until yeast is foamy, about 10 minutes. Add sponge and 2 tablespoons olive oil; mix, using the paddle, on low speed, about 2 minutes.

2. Add flour, salt, and remaining water; mix 1 minute more. Change to the dough hook, and mix on medium-low speed until dough is soft and smooth, 6 minutes. Or knead by hand, 15 to 20 minutes.

3. Transfer dough to a lightly floured surface, and knead by hand four or five turns into a ball. Place the dough, smooth side up, in a large, lightly oiled bowl and cover with plastic wrap. Let stand in a warm place until doubled in bulk, about 2 1/2 hours.

4. Brush two 9-by-5-inch loaf pans liberally with olive oil, and pour 1 tablespoon olive oil into each. Turn dough out onto a lightly floured surface, and cut off a 2-ounce piece of dough. Using fingertips, flatten the dough into a 4-by-5-inch rectangle. Spread with about 1 teaspoon olive paste, roll up tightly, and pinch the long edge to seal. Place roll, seam side down, in the prepared pan. Repeat this process until you have filled the bottom of the pan with the rolls fitting snugly; the pan should accommodate about nine. Repeat process with remaining dough and pan. Cover with lightly oiled plastic wrap, and let rise for 1 hour. Thirty minutes before this final rise is completed, place a baking stone, if using, in lower third of oven and an empty baking pan on the lowest shelf. Heat oven to 450 degrees.

5. Use a razor blade to make a lengthwise slash on each roll until olive paste is visible. Transfer loaf pans to the oven; quickly pour 2 cups of very hot water into the heated baking pan to create steam, and close the oven door. Bake until dark golden brown, about 30 to 40 minutes. Remove pans from the oven, and turn rolls out onto a wire rack to cool. If the bottom and sides of the loaves are not dark enough, return loaves without the pans to the oven, and bake until golden, about 10 more minutes. When finished baking, brush tops with remaining 1 tablespoon olive oil, and let cool on wire racks for at least 30 minutes before serving.