Combine 3 1/2 cups flour and next 3 ingredients; add oil and next 4 ingredients, and beat at low speed with a heavy-duty electric mixer until blended.
Add 1 1/3 cups hot water; beat at medium speed until blended. Turn dough out onto a lightly floured surface, and knead until smooth and elastic (5 to 10 minutes), adding remaining flour as needed. Place dough in a well-greased bowl, turning to grease top.
Let rise in a warm place (85°), free from drafts, 1 hour or until doubled in bulk.
Punch dough down; turn out onto a lightly floured surface, and knead lightly 4 or 5 times. Divide dough in half. Shape each portion into a round loaf, and place on a lightly greased baking sheet sprinkled with cornmeal.
Cover and let rise in a warm place, free from drafts, 45 minutes or until doubled in bulk. Make 1/2-inch-deep slashes in top of each loaf with a sharp knife. Combine egg and 1 tablespoon water, stirring well; gently brush mixture over loaves.
Place a shallow pan on lower oven rack; fill with boiling water. Place loaves on middle rack.
Bake at 400° for 25 to 30 minutes or until loaves sound hollow when tapped. Remove from pans immediately; cool on wire racks.