Step 1

Start by making the dough: Place 1¼ cups lukewarm water in a small bowl. Sprinkle with 2 packets active dry or instant yeast and ½ tsp of the granulated sugar, and stir to combine. Let sit until foamy on top, about 5 minutes. If it doesn’t smelly “yeasty” or bubble up, throw it out and start again with new yeast. Meanwhile, place 1½ cups of the bread flour, the remaining ¾ cup granulated sugar and 2½ tsp kosher salt in the bowl of a stand mixer.

Step 2

When the yeast is ready, mix the flour mixture with the whisk attachment on medium speed until combined, 1-2 minutes. Add the water-yeast mixture and ¼ cup vegetable oil and mix on high speed until smooth, about 3 minutes.

Step 3

Stop the mixer and switch to the dough hook attachment. Add the remaining 3½ cups bread flour and 2 of the large eggs. Mix on high speed until the dough is smooth and pulling away from the sides of the bowl, about 5 minutes.

Step 4

Lightly coat a large bowl with vegetable oil and transfer the dough into the bowl. Cover the bowl with a damp kitchen towel or plastic wrap. Let rise in a warm place until doubled in bulk and puffy, about 3 hours at room temperature, or overnight in the refrigerator.

Step 5

To make the plum jam (optional): Slice the plums, discarding the pits. To a medium pot, add the plums, 1 cup of sugar and the lemon juice. Bring the mixture up to a boil, and lower it to a simmer. After 5 minutes carefully taste the hot mixture, if you would like it sweeter, add more sugar, ¼ cup at a time. I prefer to keep this jam more tart than sweet, as the challah will likely be dipped in honey. Simmer the jam for 35-45 minutes or until easily coats the back of a spoon and has substantially thickened and reduced; it will continue to thicken as it cools. Allow the jam to fully cool before using.

Step 6

If the challah dough has been refrigerated, let it sit at room temperature for 1 hour. Line a baking sheet with parchment paper or a silicone baking mat.

Step 7

Transfer the dough onto a very lightly floured work surface. Divide into 2 portions (about 22 oz each).

Step 8

Divide half of the dough into the 4 equal-sized pieces, or into the number of strands you intend to braid with. Roll out each piece of dough into a long rectangular shape, about 12” long and 3-4” wide. Add 1-2 tsp plum jam to the center of the dough. Top the jam with a sprinkle of chopped rosemary. Fold over the dough and firmly seal it shut, then roll the dough into a long strand. If the strand splits a little, just press it closed again; minor splitting will not be a problem. After filling each strand, braid your challah. Repeat the process with the remaining half of the dough.

Step 9

Transfer the braided challahs to the baking sheet, spacing them evenly apart. Let the challah rise uncovered until risen by about ½ inch and puffed, 25-35 minutes. This step is very important to ensure a light and fluffy challah.

Step 10

Meanwhile, arrange a rack in the middle of the oven and heat the oven to 375ºF. Place the remaining 1 large egg in a small bowl and beat with a fork to break up.

Step 11

Brush the egg wash liberally over the challah. Sprinkle each loaf with 1-2 Tbsp chopped rosemary, and 1 Tbsp turbinado sugar, if desired.

Step 12

Bake until the challah is golden on the outside and sounds hollow when you “knock” on the bottom, 24-28 minutes. Transfer to a wire rack and let cool completely before serving or freezing.