Challah Bread

In a small bowl, dissolve yeast and 1 1/2 tbsp sugar in 2 cups warm water (110°). Cover and set aside for 10 minutes or until bubbles form. In the bowl of a stand mixer fitted with dough hook, combine flour, remaining 3/4 cup sugar, oil, salt, 1 whole egg, and 1 egg white. Mix on very low speed.
With mixer running, slowly add 1/2 cup warm water and continue to knead for 5 minutes.
The dough should feel soft and not too sticky. Transfer dough to an oiled bowl, cover with a towel, and allow to rest in a warm place for 1 hour or until it has doubled in size. Punch down the dough, cover it, and let it rise again in a warm place for 30 minutes.
Coat two 8" cast-iron skillets with nonstick cooking spray.
Turn dough out onto a lightly floured surface and divide into 8 equal balls. Roll each ball into a strand about 12" long. Weave 2 horizontal and 2 vertical strands to form a hashtag. Braid strands, moving right to left, always taking the strand underneath and crossing it over the next strand until a circle has formed. Repeat to form second challah.
Tuck remaining ends under, and place each challah in one of the prepared cast-iron pans.
In a small bowl, beat together remaining egg yolk and 1 tsp water; brush top of each challah with egg wash.
Set pans in a warm place; allow dough to rise, uncovered, for 1 hour or until doubled in size. Preheat oven to 350°.
Bake for 35-40 minutes, until golden brown. Let cool before serving.