Step 1

Add the water, yeast, flour, and salt to the bowl of a stand mixer. Mix on low with the dough hook for about 2 minutes.

Step 2

Cover the bowl and let stand for 30 minutes.

Step 3

Place the mixture into a covered bowl with enough room to expand, and refrigerate it for 8 to 24 hours.

Step 4

In the bowl of a stand mixer, fitted with the dough hook, add the water and flours. Mix on low for 2 minutes to combine the ingredients and then let the dough rest in the bowl for 20 minutes.

Step 5

Add the pâte fermentée pieces, the salt, and the yeast. Mix on low for 2 minutes.

Step 6

Increase the speed to medium and mix for about 4 minutes, until the dough is smooth and elastic.

Step 7

Transfer the dough to an oiled bowl and cover with plastic wrap and let rise at room temperature for 1 1/2 to 2 hours, until the dough is puffy. If you want to refrigerate the dough, let it rise at room temperature for 45 minutes, fold the dough, and then transfer it to the refrigerator for 4 to 12 hours.

Step 8

Turn the dough out onto a lightly floured work surface and shape it into a ball. Cover and let rest for 10 minutes if it's room temperature and 45 minutes if it is cold.

Step 9

Shape the dough into a batard about 12 inches long, 4 inches wide, and 3 inches high. Line a peel or the back of a baking sheet with parchment, and place the batard, seem side down, on the parchment. Cover loosely with plastic wrap. Let rise about an hour, until puffy and the dough passes the "finger dent test." (Poking it with your finger leaves a dent)

Step 10

Prepare the oven with a pizza stone on the middle rack, and a pan on the lowest rack and heat the oven to 500 degrees F. When the loaf is ready, place two cups of ice cubes in the steam pan.

Step 11

Score the loaf with one long slash, lengthwise and slide it, parchment and all, onto the baking stone. Reduce the oven temperature to 450 degrees F.

Step 12

Bake the bread for about 45 minutes, until it reaches an internal temperature of about 200 degrees F.

Step 13

Cool completely on a wire rack.