Add bread flour, yeast, and salt to a mixing bowl. Then, whisk together water, oil, eggs, and sugar in a separate bowl until sugar has dissolved completely.
Start the mixing process by using a dough hook at a slow speed, and gradually add water and oil mixture to the flour mixture.
Mix until the dough starts pulling away from the side of a mixing bowl (about 2 minutes), and use a spatula to scrape down the bowl as needed.
Then increase the speed to medium-low and mix until the dough is smooth (it'll be a little sticky); this process takes about 5-6 minutes.
Carefully transfer the dough to a lightly floured surface.
Start kneading the dough to form a smooth, round ball, about 1 minute.
Place the dough (seam side down) in a large mixing bowl lightly greased with flour or lined with plastic wrap. Cover tightly and let it rise until the size increases by half—approximately 1.5 to 2 hours.
When ready, carefully transfer the dough to a lightly floured counter. Divide it into two portions: one is smaller than the other.
Work with the bigger portion first. Cover the other one with a towel to prevent it from drying out. Divide each dough into three equal portions and stretch each into three ropes.
Pinch the far ends of the three ropes together.
You can start braiding the ropes by placing the middle strand over the other two strands alternatively.
Keep braiding until you reach the end of the ropes. Remember to pinch the bottom together to keep the braid intact.
Transfer the finished dough to a lined baking pan (cover lightly with a towel). Repeat the process with the smaller portion.
Carefully place the smaller loaf on top. Tuck the end of two loaves carefully so they can stick to each other.
Cover the dough loosely with a large plastic wrap and let it proof until the size increases by half—approximately 1 to 1.5 hours.
Preheat oven to 375F. When the dough is ready, brush it with egg wash and sprinkle with sesame seeds.
Carefully place the smaller loaf on top. Tuck the end of two loaves carefully so they can stick to each other. Cover the dough loosely with a large plastic wrap and let it proof until the size increases by half—approximately 1 to 1.5 hours.
Preheat oven to 375F.
When the dough is ready, brush it with egg wash and sprinkle with sesame seeds. Put the ready-to-bake dough in the middle rack of the oven and bake for 20 to 25 minutes. Remember to rotate it halfway.
Transfer the braided challah to a wire rack and let it cool completely before serving.