Knead in mixer for 7 minutes (or by hand for 8 to 10 minutes) adding white flour as necessary.
Let rise to double in a covered, greased bowl, and punch down again.
Form into 2 oblong or round loaves, and place on a parchment-lined baking sheet.
Cover with damp towel.
Allow to rise to about double again.
Brush with beaten egg white and slash the top of each loaf.
Bake at 400° F for 25 to 30 minutes.