What You'll Need
1 tablespoon active dry yeast
1/2 cup (100 g) plus 1 teaspoon sugar
1 cup (240 ml) warm water
4 1/2-5 cups (630-700 g) All Purpose Flour
1 1/2 teaspoons kosher salt
1/3 cup (75 ml) vegetable oil, plus more for bowl
3 eggs, divided
Sesame seeds for topping, optional
Stir together the yeast, 1 teaspoon sugar, and warm water and let sit until foamy.
In a large bowl, whisk together 4 1/2 cups of the flour, the remaining 1/2 cup sugar, and the salt.
Add the oil and 2 of the eggs to the yeast mixture and whisk to combine. Add the flour mixture and stir until a shaggy dough forms. Turn the dough out onto a lightly floured surface and knead, adding up to 1/2 cup (70 g) additional flour, a little at a time as needed, until the dough is supple and elastic, about 10 mins. (The dough can also be kneaded in a stand mixer fit with a dough hook).
Grease a large bowl with a little oil, add the challah, and turn to coat. Cover and let rise until doubled in size, about 2 hours.
Deflate the dough and divide in half. Divide each half into thirds and roll each third into a long rope. Braid the ropes into two braided loaves (3 strands each), and place on a large, rimmed baking sheet lined with parchment paper. Let rise until puffed, another 30 to 60 minutes.
Meanwhile, preheat the oven to 375F (190C). Whisk the remaining egg in a bowl, and brush a layer of egg wash over each loaf. Sprinkle tops with sesame seeds, if desired. Bake until deep golden brown and cooked through (registering 195F on a digital thermometer), 25 to 35 minutes. Transfer loaves to a wire rack to cool for 15 minutes before slicing.
Makes 2 loaves.