Combine 1/2 cup warm water, yeast and 1/8 tsp. sugar in a small bowl, stir and set aside.
Combine boiling water, cornmeal, brown sugar and salt in a large bowl. Let stand about 30 minutes until mixture cools to around 100°F. Fold in rye flour, whole wheat flour and yeast mixture; beat at medium speed 3-5 minutes. Cover and let stand 15-20 minutes.
Add vegetable oil, egg and 1 cup bread flour. Beat again, at medium speed 3-5 minutes or until smooth. Stir in enough remaining bread flour to form a ball of dough that pulls away from sides of the bowl. Place dough on a lightly floured surface; knead 8-10 minutes until smooth and elastic. Place dough in large greased bowl; turn dough so greased side is up. Cover; let rise until double, about 40 minutes.
Punch dough down gently and let rest 10 minutes. Preheat oven to 375°F. Grease either 2 pie plates or 2 baking sheets for round loaves; or loaf pans (8-1/2 x 4-/12-inch) for rectangle loaves. Divide dough in half; shape each half into round or rectangle loaves. Place in prepared bakeware. Cover and let rise in a warm (85-95°F) draft free place until loaves have doubled in size (about 20 minutes) and when lightly touched, a small indention stays.
Bake loaves 35-40 minutes until golden brown. Remove bread from pans to cooling racks. Cool loaves about 30 minutes before slicing or wrapping.