Ensure your sourdough starter is well-fed and bubbly, feeding it 4-12 hours before beginning the recipe.

The evening prior, combine all the ingredients in a stand mixer. Knead until the dough is smooth, glossy, and pulls away from the bowl, which typically takes about 20 minutes.

Cover the dough with plastic wrap, a damp towel, or a tight lid, and let it rise at room temperature for approximately 10 hours or until it has doubled in size.

In the morning, divide the dough into four equal parts.

Roll each piece into a long rectangle, about 18-20 inches in length and 3-4 inches wide, then shape each into a skinny rope.

Lay the four ropes on the counter, aligning them together, and pinch the ends.

Begin braiding by taking the second rope from the right and crossing it under the rope to its left, then over the leftmost rope.

Next, move the rightmost rope over the rope to its left, under the middle rope, and finally over the leftmost rope.

Repeat this pattern until the entire loaf is braided. Pinch the ends together and tuck them under the loaf.

Place the braided dough into a greased 9×13 baking dish or on a cookie sheet.

Let the dough rise again for about an hour.

Preheat your oven to 425°F (220°C).

Prepare the egg wash by beating an egg yolk with a tablespoon of water and brush it over the loaf.

Bake the challah for about 25 minutes, until it starts to turn golden brown.