This challah recipe is from a favorite cookbook, Zahav, by chef and restauranteur Michael Solomonov. His recipe is simple and reliable, producing a beautiful and delicious challah bread. The four basic ingredients in making bread are flour, yeast, water, and salt. Challah dough is enriched with eggs, oil and a little sugar to add some sweetness. Bread flour has a higher protein content than all-purpose flour and creates more gluten which gives bread the right structure and texture. This challah recipe has the dough rise twice. Rising (or proofing) is the process where yeasted breads attain their structure and height. When it looks like the dough has doubled in size, use your fingers to make an indentation about one-half inch into the dough. If the indentation remains, the dough is ready for the next step. Glaze the challah with an egg wash, sprinkle on the sesame seeds and bake until golden brown.
Combine the yeast and the 1 cup of warm water (between 105-110 degrees F), in a small bowl and let it sit for 5 minutes until it's foamy. Line a baking sheet with parchment paper.
In the bowl of a standing mixer with a dough hook attachment, combine the bread flour, egg yolks, sugar, salt and oil. Add the yeast mixture and knead until the dough comes together and pulls away from the sides of the bowl, about 2-3 minutes. Cover the bowl with a dry kitchen towel and let it rise until it doubles in volume. This will take about 1 - 1 1/2 hours, depending on the temperature of your kitchen.
Punch the dough down, which removes the air pockets, and divide it into 3 equal pieces. On a lightly floured surface, roll each piece into a rope about 18 inches long. Braid the ropes to form a loaf. Place the loaf on the parchment-lined baking sheet and cover with a dry kitchen towel. Let the loaf rise again until it's doubled in volume, about 30 minutes.
Pre-heat the oven to 350 F. Brush the loaf with the beaten egg and sprinkle with the sesame seeds. Bake until the challah is golden brown, about 20-25 minutes. Let it cool completely before slicing it. Store the challah at room temperature in a zip lock plastic bag.