In a large bowl, combine 1-1/2 cups flour, cornmeal, taco seasoning, sugar, yeast, onion and salt. In a large saucepan, heat the soup, water and butter to 120°-130°. Add to dry ingredients; beat on medium speed for 3 minutes. Stir in chilies and enough remaining flour to form a soft dough.
Turn onto a floured surface; knead until smooth and elastic, about 6-8 minutes. Place in a greased bowl, turning once to grease top. Cover and let rise in a warm place until doubled, about 1 hour.
Punch dough down. Shape into a loaf. Place in a greased 9x5-in. loaf pan. Cover and let rise in a warm place until doubled, about 45 minutes.
Bake at 350° for 45-50 minutes or until golden brown. Remove from pan to a wire rack. Serve warm.