Crusty, lovely-looking bread with a nut-like flavor.
Mix 5-½ cups white flour with all the whole wheat flour. Pour 2-⅓ cups of this flour mixture into a bowl and add sugar, salt, and yeast. Mix in butter and gradually stir in 2 cups water. Beat 2 minutes with electric mixer at medium speed and scrape bowl from time to time. Add sweet potatoes and ½ cup of flour mixture, and beat at igh speed for 2 minutes. Mix in remaining flour mixture, ½ cup at a time, and enough additional white flour to make a soft dough. Turn out onto floured board and knead until smooth. Place in buttered bowl, turn to grease top, coveer, and let rise until doubled, about 1 hour. Punch down and knead in 3 tablespoons sesame seed. Divide dough in half, place in 2 greased 9-inch loaf pans, cover, and let rise until doubled. Mix egg white with 1 tablespoon water and brush over tops of loaves. Sprinkle with remaining sesame seed and bake in preheated 375 degree ovenfor 35 to 40 minutes, or until done.