Pour 1/2 cup water into a very large bowl. Sprinkle in yeast and 2 tsp flour, cover, and let it sit in a warm spot to proof, about 5-10 minutes.

Stir in the remaining water and about 4 cups of the flour to make a batter, and beat with 100 strokes. Cover the bowl and set it in a draft-free spot for one hour, until a sponge develops.

Beat the eggs in a medium bowl. Reserve 1-2 Tbsp of egg to use as a glaze.

Stir in the remaining egg, salt, and oil into the sponge. Gradually stir in remaining flour to form a dough.

Knead on a floured surface for several minutes (or in a stand mixer using a dough hook) until it is smooth and elastic; add enough flour so that it doesn't stick to the counter.

Form the dough into a ball and place it in a lightly oiled bowl. Cover and set it in a draft-free spot for about 2 hours, or until the dough has risen and does not spring back when pressed. Turn the dough out onto a counter and knead it briefly. Return it to the bowl for a second rise, about 1-2 hours.

Knock the air out of the dough, and divide into 4 equal-sized balls.

Roll each ball out so that each is 60-cm strand.

Take two strands and overlap the centres of the strands so that you can make a four-strand braid. Braid the four strands loosely, and pinch and tuck the ends underneath. Place on a baking sheet lined with parchment paper. Do the same for the remaining two strands. Cover and let rise for an hour, or until the dough does not spring back when pressed.

Preheat the oven to 400F (200C).

Brush the loaves with reserved egg and sprinkle on sesame seeds. Bake for 20 minutes. Lower heat to 350F and bake for 25 more minutes. The loaves should be browned and sound hollow when tapped on the bottom.

Let bread cool thoroughly before slicing.