Overnight levain:

1. Put the sourdough starter in a small bowl and pour in the water. Mix to break up the starter. Add in the flour and mix until thorough incorporated. Cover and let it rest at room temperature for 8 -10 hours. If your house is cold, it might take longer. It was cold in my house this weekend so I put it in a proofer at 70 degrees.
2. To test if the levain is ready to use in the dough, perform the float test by taking a little bit of sourdough and dropping it in a bowl of water. If it floats, it is ready. If not, let it rest a while longer and try the test again. I had to do the float test a couple of times before my levain was ready to use in the final dough.

Final Dough:

1. Puree the beets in a blender, adding the water gradually. Puree until the mixture is completely smooth. This will take a little while unless you have a high-powered blender. Weigh the beet puree mixture, if it weighs more or less than 380 grams, you’ll either need to add more or less flour.
2. Mix the flour (reserving 250 grams), sugar and salt together in a large bowl. In a separate bowl, mix the pureed beet mixture, beaten eggs and egg whites, oil and vanilla, if using. Add the wet ingredients to the dry ingredients and mix well. Add the sourdough on top and mix thoroughly.
3. You can mix by hand or using a stand mixer. Gradually mix in up to 200 grams of flour. Let the dough rest for 30 minutes.
4. Remove the mixture to a lightly floured surface and knead the dough. Add the additional 50 grams of flour if necessary to form a supple and workable dough.
5. Clean out the bowl, and grease it lightly with oil. Shape the dough into a ball and place it back in the bowl. Cover with a kitchen towel. Let it proof for 2 -3 hours. Perform a fold after the 1st hour, place back in the bowl. Repeat at the 2nd hour. You can let the rest for the final hour or place it in the refrigerator overnight. I let the dough retard in the refrigerator overnight.

After the bulk ferment (at room temperature or cold in the refrigerator)

1. Divide the dough into 3 equal pieces and shape them into a ball. My dough balls were 452 grams each. Let them rest a few minutes, then divide each ball into 3 equal pieces (150-152 grams each).
2. To make the braids, take each piece and flatten and fold it over to remove excess air. Then shape it into a batard and seal the seams.
3. Allow the batards to rest for a few minutes before rolling out the strands. When working with cold dough, it will take a little while to roll out the strands. Just let them relax a few times to get the appropriate length. I didn’t measure the length but I do know that I rolled out the last braid a bit longer and I liked it the best. The dough had warmed up a bit by then so perhaps that’s why.
4. Place the braided loaves on a parchment-lined baking sheet and brush with egg wash. Cover gently with oiled plastic wrap so it doesn’t stick to the braids and let them proof about 1 1/2 hours, until they have grown to about 1 1/2 times their original size. If your kitchen is cold, it may take longer.
5. Preheat the oven to 350 degrees F. (or 325 degrees F. for the double braid) and place the oven rack on the middle shelf.
6. Brush the loaf again with egg wash and sprinkle the top with poppy seeds.
7. Bake the loaf for 20 minutes, rotate the pan for even baking, then bake an additional 20 to 35 minutes depending on the size of the loaf. It should register 190 degrees in the center.
8. Transfer the loaf to a wire rack and let it cool for 1 hour before slicing.