Every village on Sardinia makes its own special breads, and its rumored that there are five hundred different kinds on the island. This particular one comes from the area around Cagliari and was originally a holiday bread. It is now available every day. Formed into semicircles and called cocoeddi, it is made from a simple starter named biga, which gives the bread its special aroma, flavor and texture by producing a second fermentation. The starter can be kept in the refrigerator up to five days or can be frozen; before being used, it should be brought to room temperature, which takes about three hours.
Starter

1/4 cup warm water (105°F. to 115°F.)
1/4 teaspoon dry yeast
3/4 cup plus 4 teaspoons water, room temperature
2 1/2 cups unbleached all purpose flour Bread

2 1/2 cups warm water (105°F.°F. to 115°F.)
2 1/2 teaspoons dry yeast
3 3/4 cups unbleached all purpose flour
3 3/4 cups finely ground semolina flour
2 teaspoons sea salt Additional semolina flour

For Starter:

Combine 1/4 cup warm water and yeast in medium bowl. Let stand until yeast dissolves, about 10 minutes. Stir in 3/4 cup plus 4 teaspoons room temperature water. Add flour in 3 additions, stirring well after each addition Stir until mixture has consistency of thick sticky dough, about three minutes. Light oil large bowl. Transfer starter to a bowl. Cover with plastic; let rise at cool room temperature until tripled in volume (starter will be slightly wet and thick), at least 6 hours and up to 24 hours. (Can be made 5 days ahead. Stir down starter, cover and chill. Bring to room temperature before using.) For Bread:

Pour 2 1/2 cups warm water into large bowl of electric mixer fitted with paddle attachment. Sprinkle yeast over; let stand until dissolved, about 10 minutes. Measure 2/3 cup starter (reserve remainder for another use). Rub between fingers, allowing starter to drop into yeast mixture (starter will be stringy). Beat until some of the starter dissolves. Combine flour, 3 3/4 cups semolina and salt in large bowl. Add to yeast mixture in 3 additions; beat until incorporated. Turn out unto floured surface; knead until smooth and elastic, about 6 minutes.

Oil large bowl. Transfer dough to bowl, turning to coat with oil. Cover bowl with plastic. Let rise in warm draft-free area until doubled in volume, about 1 hour.

Butter 2 heavy large baking sheets. Punch down dough. Divide into 4 pieces. Cover 3 pieces with clean towel. Roll remaining piece on floured surface to 14x8 inch rectangle. Starting at 1 long edge, roll up dough jelly roll style. Press ends and seam to seal. Bend dough into half-circle. Using sharp knife, cut 1/2-inch-deep incisions every 1 1/2 inches in the top of the dough. Sprinkle with additional semolina. Place on a prepared sheet. Repeat rolling and shaping with remaining dough pieces.

Cover shaped dough with clean towel. Let rise in warm draft-free area until doubled, about 45.

Meanwhile, position 1 rack in bottom third. If available, place baking stone on rack and preheat oven to 450°F. Let stone heat at least 30 minutes.

Place 1 baking sheet on each stone. Bake until bread is golden brown and sounds hollow when tapped on the bottom, alternating sheets between racks halfway through baking, about 25 minutes. Cool bread on racks.

Makes 4 small loaves.