In a bowl of a standing mixer, combine the first quantity of flour, yeast, and water and use a fork to beat until smooth and thick.
Cover with a kitchen towel and let sit for 30-40 minutes until frothy.
In a medium bowl, whisk the eggs, egg yolks, and oil until blended, set aside.
Add the liquid ingredients(step 3) into the sponge (steps 1-2) and use the paddle attachment to blend it all together. (Use a wooden spoon if making by hand)
Gradually add the remaining of flour, sugar, and salt and continue to mix until it all comes into a shaggy mass. About 2-3 minutes.
Replace the paddle attachment with the dough hook and keep kneading for 6-8 minutes until the dough is smooth and the sides of the bowl are clean. (10 minutes in kneading by hands)
Spray the dough with some oil spray and cover the bowl with a plastic bag. Let rest and rise for about 2-3 hours or until double in sized.
Place the dough on a clean work surface and knead to 1 minute. Divide dough into two even pieces (each piece about 650 G / 23 oz)
Roll each piece into 30" long log and then roll one end towards the other end. Repeat with the second piece.
Place challahs each on a large baking sheet (they will rise again) brush with egg wash and sprinkle with your choice of toppings.
Let sit and rise again for about 2 hours.
Bake for 30 minutes at a 350F preheated oven.