Whole-Wheat Challah - Kosher.com

Ingredients

• 6 (1/4-ounce) packages dry yeast
• 1 and 1/2 cups sugar
• 2 cups hot water
• 2 cups seltzer
• 1/3 cup oil
• 3 and 1/2 tablespoons kosher salt
• 4 eggs, plus 1 additional egg yolk, for brushing
• 1 3-pound bag extra-fine, pre-sifted whole-wheat flour (I use Shibolim; if presifted flour is not available, you can sift it yourself)
• 1 cup wheat germ
• 1 and 3/4 cups Glicks White Flour
• Gefen Sesame Seeds, poppy seeds, or everything spice, for sprinkling (optional)