egg wash1 egg white plus 1 tablespoon water, beaten
Prepare the Dough
In the bowl of a stand mixer, dissolve the yeast in the warm water for about 3-4 minutes
When the yeast is bubbly and activated, mix in the eggs, honey, salt, melted butter and the mashed sweet potato using the paddle attachment until well blended. Remove the paddle attachment and switch to the dough hook. Add 4 cups of the flour to the mixing bowl, mixing on low speed until the dough starts to come together. Let the mixer knead the dough for about 5-7 minutes, gradually adding the flour about a 1/2 cup at a time, until the dough is not too sticky and it comes together into a ball. Turn the dough out onto a floured surface and do a few final kneads, adding a little more dough (add it in tablespoon increments) if necessary. The dough should be soft and supple, and can easily take the shape of a ball, and not too sticky.
Place the dough in a bowl lightly coated with canola oil, giving it a turn so that the the dough has a very light coat of oil. Lightly cover with a kitchen towel and place the dough in a warm spot, free from any drafts.
Let the dough rise for about 1 1/2 to 2 hours until the dough has doubled in size.
When the dough has ballooned, punch it down, turn it over, and let it chill in the refrigerator overnight. While the dough can be used right away, proofing it overnight in the refrigerator gives it a much deeper flavor. The dough will be ready to use the following morning, or even several days later if you wish.
On Baking Day
On the day you are ready to bake, remove the dough (or a portion of the dough) from the refrigerator and allow it to come to room temperature. You could do a simple three strand braid if you wish. But to create a six strand braid, divide the dough into three pieces, then divide each piece into six more pieces for a total of 18 small rounds of dough. You should have enough dough to make three challah loaves.
Take six pieces and roll each into a rope, about 1 inch thick and 12 inches long.
To braid the dough, pinch the six strands together at the top. Take the right strand and cross it all the way over the left, and take the left strand and cross it all the way over to the right. Then take the strand that is now farthest to the left and place it between the four strands down the center. Repeat this pattern until you reach end of the end of the loaf, keeping the braid as tight as possible. Pinch the end under and fluff the loaf if necessary. Repeat with the remaining dough. Let the loaves rest for an hour at room temperature to let it rise one last time.
If you wish to bake some of the braided loaves another day, freeze the loaves and let it rest before baking on another day.
Preheat the oven to 350° F with the rack placed on the lowest setting.
Lightly butter a 12" baking tray, and place one sweet potato challah on it. Brush the loaf with the egg wash. Bake for about 20-25 minutes, or until the bread is golden, crisp on the outside and sounds hollow when you tap it. Bake the remaining loaves in batches.
Let the loaves cool for at least 20 minutes before slicing. Enjoy warm with soft butter!