Make a sponge: Place the tepid water, whole-wheat flour and yeast in a large mixing bowl or in a bowl that attaches to a mixer. Stir this mixture together or do like we do and use your hands and really get in there and mush it together. Cover the mixture and allow it sit in a warm place for 30 minutes.
Add the rest of the ingredients adding only enough flour until the mixture is not wet and sticky. You many not need the entire 4 cups of flour. Knead the dough for 5 minutes until the dough is supple and smooth. Cover and let it rest for at least one hour or store the dough wrapped tightly over night in the refrigerator.
Shape the dough into your favorite loaf. Place the loaves on a lightly greases sheet pan. Cover with a clean towel and let rise for two hours.
Whisk together yolks and water, brush the loaves with the egg wash, sprinkle with seeds if using, and bake in a preheated 350°F oven until the challot are browned and make a hollow sound when tapped on the bottom (about 30-45 minutes).
Let the challot sit for at least one hour before cutting it. The baking process continues for 20 minutes after the bread is removed from the oven. Steam continues cooking the bread and making it dense and moist. Cutting the crust would allow the steam to escape.