To make the Dough: In the bowl of a stand mixer fitted with the dough hook, mix together water, yeast and 1 tablespoon sugar. Let stand 5-10 minutes until frothy and the yeast has bloomed. Meanwhile: In a separate bowl, whisk together 4 1/2 cups flour and salt.
With mixer on low speed add remaining honey, oil and 2 eggs plus egg yolk to the bowl mixing until fully combined. With mixer on low speed gradually add the sifted flour. Increase speed and knead for 5-8 minutes or until the dough is smooth. (Add additional flour 1 Tbsp. at a time until the dough pulls away from the side of the bowl.)
Turn the dough out onto a lightly floured non stick surface and turn to coat with flour kneading by hand until smooth and it's no longer sticky.
Lightly grease a large bowl, place dough into bowl turning to coat with oil. Cover and let rise for 2 hours or until doubled in size.
Gently punch down the dough and turn out onto a floured work surface. Pat into a circle about 1 1/2 inch thick. Cut into 4 even portions.
Stretch and roll dough portions into 20 inch long ropes. Lay strips parallel with farthest ends slightly pinched together touching, fanning out the strips.
Begin with floured hands, braiding ropes starting with the left outer braid weaving over, under, over. Repeat with the far right braid weaving over, under, over. Repeat until you come to the end of the braids, tucking the ends neatly under on both ends. You may need to stretch braids while braiding if they snap back. Pat with floured hands to shape.
Transfer to a large parchment lined baking pan. Cover and let rise in a draft free area for 1-2 hours or until around 1 1/2 in size.
To Bake: Preheat oven to 350°F. Uncover challah. Whisk remaining egg then use a pastry brush to brush all over bread. (At this point you can sprinkle with more salt, poppy seeds or sesame seeds.)
Bake for 25-35 minutes or until a deep golden color and an internal temperature of 195°F is reached.
Cool on a cooling rack, slice and enjoy.