Make the Biga

See recipe.

Preheat the Oven

Twenty minutes or longer before baking, set an oven rack in the middle level of the oven and preheat the oven to 325°F/160°C.

Toast and Break the Walnuts

Spread the walnuts evenly on a baking sheet and bake for 7 minutes to enhance their flavor. Stir once or twice to ensure even toasting and avoid overbrowning. Turn the walnuts onto a clean dish towel and roll and rub them around to loosen the skins. Coarsely break the nuts into a bowl, scraping off and discarding as much of the skins as possible. Cool completely.

Preheat the Oven

Forty-five minutes or longer before baking, set an oven rack at the lowest level and place the baking stone or baking sheet on it. Place a cast iron pan, lined with aluminum foil to prevent rusting, or a sheet pan on the floor of the oven. Preheat the oven to 450°F/230°C.

Slash and Bake the Bread

With a straight-edge razor blade or sharp knife, make three ½ inch deep by 2½ inch long diagonal slashes in the top of the dough. Start the first slash about 1 inch from the top end of the dough and start each of the following 2 slashes about 1 inch before the end of the preceding one.

Mist the dough with water. Quickly but gently set the baking sheet on the hot stone or baking sheet and toss a handful (about ½ cup) of ice cubes into the pan on the oven floor. Immediately shut the door and bake for 5 minutes. Lower the heat to 400°F/200°C and continue baking for 15 minutes. For even baking, rotate the pan halfway around.

Continue baking for 15 to 20 minutes, or until the bread is golden brown and a skewer inserted into the center comes out almost clean. (An instant-read thermometer inserted into the center should read about 205°F/96°C.)

Cool the Bread

Remove the bread from the oven and transfer it from the baking sheet onto a wire rack to cool completely, top-side up, at least 2 hours.

Make the Dough

Bread Machine Method Into the container of the bread machine, pour the water. Use sharp scissors, dipped in water if it is sticky, to cut the biga into many small pieces, letting them drop into the water. Add the flour and yeast. Program the machine to mix for 3 minutes and set it to go through the 3 minutes of mixing. Let the dough rest (autolyse) for 20 minutes.

Program the machine to knead for 10 minutes. Add the salt and set the machine to go through the knead cycle, which will include 3 minutes of mixing and 7 minutes of kneading.

Let the dough rest for 20 minutes. Add the raisins and walnuts and reset the machine to mix for 3 minutes.

Stand Mixer Method Into the bowl of a stand mixer fitted with the dough hook, pour the water. Use sharp scissors, dipped in water if it is sticky, to cut the biga into many small pieces, letting them drop into the water. Add the flour and yeast, and mix on low speed for about 1 minute, or until the flour is moistened enough to form a rough dough. Scrape down any bits of dough from the sides of the bowl. Sprinkle on the salt and knead the dough on medium speed for about 7 minutes. The dough should be very elastic and smooth, and sticky enough to cling to your fingers. Cover the top of the bowl with plastic wrap and let the dough rest for 20 minutes. Add the raisins and walnuts and knead on low speed for about 1 minute, or until evenly incorporated.

Let the Dough Rise Twice

Using a spatula or dough scraper that has been lightly coated with nonstick cooking spray, scrape the dough into a 2 quart/2 liter dough rising container or bowl that has been lightly coated with nonstick cooking spray. Push down the dough and lightly coat the surface with nonstick cooking spray. (The dough should weigh about 18 ounces/510 grams.) Cover the container with a lid or plastic wrap. With a piece of tape, mark the side of the container at approximately where double the height of the dough should be after rising. Let the dough rise in a warm place (ideally at 75° to 85°F/24° to 29°C) until it reaches the mark, 1 to 1½ hours. (See recommended rising environments.)

Using a spatula or dough scraper that has been lightly coated with nonstick cooking spray, turn the dough onto a lightly floured counter and gently press down on the dough to form a rectangle. Give it a four-sided stretch and fold (gently stretch out one side at a time and fold it into the center). Round the corners and set it back into the container.

Again, lightly coat the surface of the dough with nonstick cooking spray, cover with plastic wrap, and mark where double the height should now be after rising. (The dough will fill the container fuller than before because it is puffier with air.) Let it rise until it reaches the mark, about 45 minutes to 1 hour. If time allows, for extra flavor, give the bread the second rise overnight in the refrigerator instead.

Turn the dough onto a lightly floured counter and press the dough down to flatten it slightly. The dough will still be sticky, but use only as much flour as absolutely necessary. Cover the dough and let it rest for 20 minutes before shaping (1 hour if it has been refrigerated).

Shape the Dough and Let It Rise

Gently flatten the dough into a 7 by 5 inch rectangle, with the longer side facing you. Fold down the two upper corners about 3 inches to form a triangle and press down the dough. Set the apricots in a staggered row lengthwise across the dough, under the triangle. Starting from the top, roll the dough to encase the apricots. When you reach the bottom edge of the dough, pinch it firmly against the outside of the dough to make a tight seam. The torpedo-shaped dough should be about 10 by 3 by 2 inches high. Set it on the prepared baking sheet.

Cover the dough loosely with plastic wrap that has been lightly coated with cooking spray. Let the dough rise in a warm place (ideally at 75° to 85°F/24° to 29°C) for about 45 minutes to 1 hour, until about 11 by 3½ by 2⅛ inches high, and when pressed gently with a fingertip, the depression fills in very slowly.