In the large bowl of a stand mixer fitted with the dough hook, put the bread flour, 1 cup unbleached flour, yeast, sugar and salt. Stir to combine.
In a small bowl, beat 3 eggs. Add the oil to the eggs and add both to the flour mixture. Stir to combine.
Stir in water and mix lightly.
Turn the mixer to medium speed. As the dough kneads, sprinkle small amounts of the unbleached flour around the bowl to keep the dough on the hook. Continue to sprinkle in flour as the dough kneads. After 5-10 minutes, the dough should be very smooth and not sticking to the sides or bottom of the bowl.
Remove the dough hook. Cover the dough with plastic wrap. Let it rest in the bowl for 20-30 minutes.
Sprinkle flour over the dough and use a knife or spatula to loosen it from the bowl. Turn it onto a lightly floured surface and press it gently into a large rectangle. Using a sharp knife, divide the dough into as many pieces as you will need to braid each loaf. This recipe makes two loaves so you will need at least 6 pieces for both.
Form each piece into a ball and then roll it between your hands to make a rope. Put the short rope onto the counter and roll under your palms until the rope strand is approximately 12 inches. Repeat for each piece.
Coat each strand lightly with flour, shaking off any excess. Attach the strands at the top end, fanning them out. Braid as desired. Turn each end of the loaf under.
Place loaves on a baking sheet covered with a nonstick liner or parchment paper. If loaves are very large, use a second baking sheet so they have room to rise. You may also use nonstick spray on the sheets.
Beat the fourth egg with one tablespoon of water. Using a pastry brush, coat top and sides of both loaves with egg wash.
Turn your oven to 200 degrees. When the oven has reached temperature, set a timer for one minute. When timer sounds, turn oven off immediately. Place the loaves on the center rack of the oven. Close oven door and let loaves rise for 30 minutes.
Leave the loaves in the oven and raise the temperature to 350 degrees. Bake for 40-50 minutes or until brown on top and bottom. An instant-read thermometer should read 190-205 degrees.
Remove loaves from oven and place immediately on a wire rack for at least one hour. Cool completely before storing in a plastic bag.
This recipe was adapted from The New Jewish Holiday Cookbook by Gloria Kaufer Greene.