In a large mixing bowl, dissolve the yeast and 1 tablespoon of sugar in the warm water. Let it sit for about 5 minutes until frothy.
Add the remaining sugar, oil, eggs, and salt to the yeast mixture. Gradually add the flour, one cup at a time, until a dough forms.
Knead the dough on a floured surface for about 10 minutes until smooth and elastic. Place the dough in a greased bowl, cover with a damp cloth, and let it rise in a warm place for about 1.5 hours or until doubled in size.
Punch down the dough and divide it into three equal parts. Roll each part into a long rope and braid them together. Place the braided loaf on a baking sheet lined with parchment paper.
Cover the loaf with a damp cloth and let it rise for another 30 minutes. Preheat your oven to 375°F (190°C).
Mix the egg yolk with 1 tablespoon of water and brush it over the loaf. Bake for 30 minutes or until golden brown. Let it cool on a wire rack before serving.