For The Sponge:
1/4 teaspoon French Sourdough Starter (may be purchased online at: kingarthurflour.com) or use 1/4 tsp. pre-packaged sourdough starter
2 cups Unbleached All-Purpose Flour
1 cup warm water
For The Dough
All of the sponge (above)
3 cups Unbleached All-Purpose Flour
3/4 cup warm water
1 1/2 teaspoons sea salt
1/2 teaspoon instant yeast
Combine the sponge ingredients and allow the mixture to rest for 18 to 20 hours at room temperature. When ready, the sponge should have expanded, and developed bubbles and a pleasing aroma. (You may do this step up to 7 days ahead, then refrigerate until ready to use.)
Combine all of the dough ingredients (including all of the sponge) and mix them together by hand, mixer or bread machine until they're well-combined. Allow the mixture to rest for 20 to 30 minutes. This resting period, the autolyse, allows the gluten to relax, and the flour to absorb the water.
Knead the dough by hand, mixer or bread machine until it's firm, slightly sticky, and elastic. Allow the dough to rise, covered, for 2 to 3 hours in a moderately warm spot (not over 90°F/32°C), or until it's puffy (though not necessarily doubled in bulk).
Turn the dough out onto a lightly greased work surface, divide it in half, and form each half into a round. Let the rounds rest, covered, for about 20 minutes. Form the rounds into the desired shape (round, oval, or baguette).
Note: raising the loaves in a couche or dough-rising basket will help them achieve a thick, chewy crust. Let the loaves rise, covered, for 2 or more hours. They should almost double in size.
Preheat your oven to 475°F (246°C) for 30 minutes. Turn the loaves onto a piece of parchment paper placed on a baker's peel (if you're using a baking stone), or onto a parchment-lined baking sheet.
Slash the loaves several times using a lame, a sharp knife or a razor blade. Spritz them with water, and place them in the oven. Spritz them with water again after 30 seconds, again after 1 minute, and once more at 2 minutes. Then turn the oven down to 450°F (232°C) and bake for 18 to 25 minutes. The bread should be golden and sound hollow when tapped; its internal temperature should read 195°F (90°C) on an instant-read thermometer. Remove the bread from the oven, and transfer it to a rack to cool.
For nice big fissures (gaps or holes) in your loaves' interior, dust them with flour, cover, then refrigerate overnight. Next day, remove the loaves from the fridge, and let them rest, covered, at room temperature while you preheat your oven for 30 minutes. Uncover and bake as directed above.
Makes: 2 loaves.
Source: King Arthur Flour
Date: May 23, 2003