Sprinkle the yeast over the water in a large mixing bowl. Let it rest for 5 minutes or until it begins to bubble. Stir well, then stir in the salt and half of the flour. Add more flour, a quarter-cup at a time, until you have a thick mass that pulls away from the sides of the bowl.

Turn the dough out onto a lightly floured surface. Sprinkle over with another 1/4 cup of flour and knead for about 7 minutes, adding more flour as needed, until the dough is smooth and elastic.

Shape the dough into a ball and let it rest on the work surface. Clean out the mixing bowl, butter it lightly, and return the dough to the bowl. Turn it around several times to coat it with butter, then cover the bowl with plastic wrap or a damp towel, and put it in a warm place (about 80°F). Let the dough rise until doubled in volume.

Preheat the oven to 400°F.

When the dough has risen, punch it down, remove it from the bowl, and knead for 2 minutes to expel any air bubbles. Divide the dough into twelve pieces with a knife. Form each piece into a tight ball, place on a lightly floured surface, cover with plastic wrap or a damp towel, and let rise for a half-hour.

Dust the top of the loaves with flour and flatten them into 6-7" circles. Place them on lightly floured baking sheets, four loaves to a sheet, and cover two of the sheets with a damp towel. Bake one sheet of pitas at a time. Place on the center rack of the oven and bake for about 5 minutes, until the bottoms are just barely golden and the loaves have puffed up. Do not over-bake; these loaves should be soft, not crusty. Serve hot. Makes 12 loaves.