1 1/2 tablespoons yeast
2 1/2 cups warm water
2 teaspoons salt
2 tablespoons vegetable oil
7 cups all-purpose flour
1 tablespoon cornmeal
1 egg white
1 tablespoon water
In a large bowl (or bowl of an electric mixer), dissolve yeast in warm water. Let stand until creamy, about 10 minutes.
Add salt, oil and 4 cups flour to the yeast mixture; beat well. Stir in the remaining flour, 1/2 cup at a time, beating well with an electric mixer at medium speed after each addition until a soft but not sticky dough is formed (you may not need to use all 7 cups).
When the dough has pulled together, turn it out onto a lightly floured surface and knead until smooth and elastic, about 6 minutes (or let knead in an electric mixer). Lightly oil a large bowl, place the dough in the bowl and turn to coat with oil. Cover with a damp cloth and let rise in a warm place until doubled in volume, about 40 minutes. Punch dough down, and divide into 6-8 equal portions. Shape each portion into a round ball. Place loaves on lightly greased baking sheets sprinkled with cornmeal (or use silpat liners or parchment paper).
Cover and let rise in a warm place, free from drafts, until doubled in bulk, about 35 minutes.
Preheat oven to 400 degrees. In a small bowl, beat together egg white and 1 tablespoon water; lightly brush the loaves with half of this egg wash. Bake in preheated oven for 15 minutes. Brush with remaining egg mixture, and bake 10 to 15 more minutes or until golden. Cool on wire racks.