Make the stiff starter (levain): Knead starter into water until partially dissolved, then add flour. Knead dough until smooth. If starter still has dry spots, add water a half teaspoon at a time. Place in a covered container where it will ferment and increase 4x in volume. Let ferment 8-12 hours.
Mix and autolyse: In a large bowl, beat together water, 2 eggs, salt, oil, and honey until well mixed and salt is dissolved. With your hands, wooden spoon, or using dough hook in a mixer, mix in all flour at once. Once no dry bits of flour are left, cover and rest for a long autolyse with whole wheat for 30 minutes up to 2 hours.
Add the starter: After autolyse, it is time to add 200g of the firm starter. If using mixer, add the starter to the whole wheat challah dough and knead with dough hook until fully incorporated, scraping as needed. If mixing by hand, turn whole wheat challah dough out onto a work surface, knead in the starter until dough is smooth and the starter is fully incorporated.
Bulk Fermentation: Prepare a clean bowl and place dough into bowl. Cover and ferment 2-3 hours.
Stretch and fold: To further strengthen dough during bulk fermentation, pull up one quarter of the dough and fold it over the middle. Repeat this process with the other three quarters of the dough. Re-cover the dough. This step can be done up to 4 times for maximum development of dough strength, if desired. Recover the dough after each stretch and fold.
Prepare a baking sheet: Line a baking sheet with parchment paper, preferably one with no sides like a cookie sheet. Decide whether to make one large loaf or two medium loaves. For two medium loaves, divide the dough into two equal parts.
Divide: Lightly flour aclean work surface and transfer the dough from the bowl to the work surface.Divide the dough into 4 equal pieces (if making 2 loaves) or 2 equal pieces (ifmaking 1 loaf), either visually or by weighing the dough on the scale.
Shape: Line two bakingsheets with parchment paper. Lightly flour the work surface and roll out 1piece of dough into a 5- by-15-inch rectangle (double the length if making 1large loaf). Starting at a long side, roll up the dough until it is curled intoa long rope shape. Roll and stretch the dough rope with your hands or hold the endsand gently shake and stretch the rope until it is about 18 inches long. Repeatwith the remaining pieces of dough.
Braiding: Take two ropes of the dough and cross themover each other into an “X”shape. Take the upper two sections of the ropes of dough and pull down towardthe bottom so all four ends are pointed downward. Take four small pieces ofpaper and label each one with a number: 1, 2, 3, 4. Put the pieces of paperbelow the ropes of dough, from left to right. As you follow the braiding steps,move each number to align with the rope’s new position. To start: Bring1 over 2, 3 over 4, 4 over 1, 2 over 4, 1 over 3, 3 over 2, 4 over 3, and 1under 2. Tuck all the strands under and seal them against the loaf. The goal ofthe braiding is to have an alternating and even pattern that comes up higher inthe center of the loaf. Hold the ends of the loaf and stretch it if needed tohelp make the shape more even.
Proof: Transfer the loaf or loaves onto the parchment lined baking sheet. Cover with plastic wrap or a slightly moistened kitchen towel and proof at room temperature for 4 to 6hours, until the loaves are about tripled in size. Check proof readiness using poke test, poking dough should leave a slight dent.
Preheat: 30-45 minutes before the end of the proofing period, begin to preheat oven to 350º F with a baking stone in the center of the oven--or bake on a flat baking sheet, and a metal pan of water filled halfway with water on the lowest rack to fill the oven with steam.
Egg wash: Whisk 1 egg with 1 tablespoon of water and brush it onto the loaf or loaves. Sprinkle the tops with poppy seeds or sesame seeds, if you’d like.
Bake: Carefully slide the parchment with the loaf or loaves onto the preheated baking stone. Spray some water on the walls of the oven to add additional steam then quickly close the door to trap the steam. Bake for 25 minutes with the steam. Remove the steam tray and continue to bake for 10 to 15 minutes longer or until the loaves are a shiny golden brown and have an internal temperature of 190°F.
Allow to cool 20-60 minutes then enjoy the most delicious Sourdough Whole Wheat Challah ever!