2 packages dry yeast
2 tablespoons granulated sugar
1 1/2 tablespoons salt
2 cups warm water
6 to 7 cups all-purpose flour
2 tablespoons olive oil
Put yeast and sugar in 1/2 cup very warm water and stir to dissolve and allow to "proof."
Meanwhile, measure salt and 2 cups of flour into mixing bowl. After yeast has "proofed," add enough very warm water to bring level to 2 cups. Add to flour and salt and mix with a spoon. As dough begins to form, add 2 more cups flour and 2 tablespoons oil. Using dough hook on electric mixer (or mix by hand), add 1 or 1 1/2 cups more flour, mixing by machine or by hand to get a stiff but pliable dough. Knead vigorously 10 minutes, finishing by kneading by hand on floured board, working up to 1/2 to 1 more cups flour into dough until it is smooth and elastic. Scrape out mixing bowl, wash and dry, and coat inside of bowl with oil or liquid margarine. Turn dough around in bowl several times to coat entire surface with oil or margarine. Cover with towel dampened in warm water, and place in draft-free place to rise until double in bulk, about 1 to 1 1/2 hours.
Return dough to lightly floured board and punch down to remove as much trapped air and gas as possible. This should not take more than a minute or so. Using a knife, cut dough into 4 equal pieces. Shape each into an elongated loaf about 15 inches long and 1 inch wide, rolling back and forth to smooth out the loaf. Place loaves on a lightly greased cornmeal-dusted baking sheet. Using a very sharp knife or razor blade, make slashes in loaves diagonally about 4 inches apart. Place baking sheets in cold oven and allow to rise again until doubled or more in size, about 30 to 45 minutes.
Turn on oven to 400 degrees F, but do not remove bread from oven. After 5 minutes brush bread with mixture of egg white mixed with 2 tablespoons water and, while damp, sprinkle with sesame seeds and coarse or kosher salt. Turn heat to 350 degrees F and continue baking 40 minutes. Test loaves by tapping on bottom . If sound is hollow, bread is done.
Remove from oven and place on racks to cool. Loaves may be frozen if well wrapped when completely cool.