Place the water, salt, and sugar in the bowl of a heavy-duty electric mixer (KitchenAid K5A2 model works best). Stir to dissolve the sugar. Add the yeast and stir to dissolve. Stir in the beaten eggs and the oil. Beat in 5 cups of the weighed-out flour to make a batter. Beat for 5 minutes or until the batter begins to pull away from the sides of the bowl. Knead in the remaining flour by machine until smooth. Place the dough on a clean countertop and cover it with a large metal bowl. Allow the dough to rise until double in bulk. Punch the dough down and allow it to rise again. Punch the dough down again and divide it in half. Cut each half into thirds. Roll 3 of the pieces into ropes about 41 cm long with your hands. Join 1 end of each rope and press together with the heel of your hand. Alternately, braid the 3 ropse together and press the other 3 ends together with the heel of your hand.. Sprinkle a large baking sheet with a little of the cornmeal. Place the braided dough on the sheet pan and allow it to double in bulk again. Repeat the process with the remaining dough. Allow the dough to rise until double in bulk. Beat the 2 egg yolks and 1 tablespoon of water together for the egg wash. Lightly brush both risen braided doughs. Sprinkle with sesame seeds. Bake in a preheated 180ºC oven for 50 to 60 minutes, until loaves are deep golden brown and sound hollow when tapped on the bottoms with your finger. Remove to a cooling rack.