Dissolve the yeast in one-quarter cup of water in a nonmetallic bowl. Add the remaining water. Using a wooden or plastic spoon, stir in the flour, half a cup at a time, until smooth (traditionally 100 strokes).

Cover with a lid or plastic wrap and let stand at room temperature until the mixture is light and foamy (at least one hour and up to 12 hours).

Stir down the sponge. Stir in the sugar, oil, and salt. Add the durum flour and let stand for 20 minutes. (This allows the slightly coarse semolina to hydrate and became a part of the dough.)

Gradually add enough white flour to make a soft dough.

On a lightly floured surface, knead the dough until smooth and elastic (about 10 minutes). Place in a greased bowl, turning to coat. Cover and let rise until doubled in bulk (about one and a half hours).

Punch down the dough and divide in half, thirds, or quarters. Shape into oblong loaves (about 18 inches long for thirds) or rounds and place on Gefen Parchment Paper-lined or greased baking sheets. Cover loosely with plastic wrap or a towel and let rise in a warm place until nearly doubled in bulk (about 35 minutes).

Position a rack in the lower third of oven. Preheat the oven to 375°F (190°C).

Slash three or four quarter- inch-deep diagonal slashes (hold the razor at about a 30° angle, not straight up) in the top of the loaves. (This causes the slashes to swell and the crust to thicken around the lips during baking. For longer loaves, increase the number of slashes up to ten.) Bake until the bread is golden brown and hollow-sounding when tapped on the bottom (35 to 45 minutes). Remove from the pans and let cool on a rack.