Scald the milk and combine it in a mixing bowl with the honey, salt, and butter. Stir well and cool to lukewarm. Dissolve the yeast in the warm water and combine with the milk mixture. Add the white flour and beat vigorously for 1 minute or until the batter is very smooth. Add the caraway seeds, onion, wheat germ and enough rye flour so that the dough is firm enough to knead. Turn the dough out onto a floured surface and knead for 8 minutes. Wash out the mixing bowl. Dry it well and coat it with oil or butter. Place the dough in the bowl and turn it around so that the dough is coated on all sides. Cover and let rise in a warm place for 1 hour or until doubled. Punch the dough down and roll it out with your hands into a long rope about 1 to 1 1/2-inch pieces and shape into buns. Preheat the oven to 400°F. Beat the egg with the water and brush the tops of the buns. Bake 12 to 15 minutes or until nicely browned.