Directions

1. Preheat the oven to 350 degrees. Turn it off after it reaches temperature, so that when it's time for the dough to rise, the oven will be warm, but not hot.
2. Lightly flour (or line with parchment paper) a baking sheet and set it aside.
3. In a large mixing bowl, whisk the yeast and the pinch of sugar into 2/3 cup warm water, and let sit to activate, 3-4 minutes (it will become foamy). 
4. Whisk in the remaining sugar, the olive oil, 2 of the eggs, and the salt. Continue whisking until completely incorporated.
5. Slowly add the flour, stirring as you go. Eventually, you should have a soft, rich dough.
6. Flour a smooth, clean surface (like a countertop or large cutting board) and turn the dough out onto it. 
7. Knead the dough for 8-10 minutes, until smooth and elastic. Form it into a large ball.
8. Clean the dough debris the bowl you mixed it in, and pour about 2 tbsp olive oil into it. 
9. Place the dough in the oiled ball and roll it around to make sure it is completely covered with oil.
10. Cover the bowl with a clean dish towel and place in the warm (but not hot) oven.
11. Let rise for 1 hour, or until roughly doubled in size.
12. Now it's time to weave the challah. There are a few ways to go about this, all of them gorgeous and awesome: You can do it the Deb (of SmittenKitchen) way, the Tori of The Shiksa in the Kitchen way, or you can do it the Gabi Moskowitz, 1989 Graduate of Beth Ami Hebrew School Sunday Challah-Making Class way, which is to sort of braid it like you would hair, and then tuck the messy bits under so no one can see them (which, for the record, I also do with my hair). 
13. Transfer the braided challah to the prepared baking sheet.
14. In a small bowl, whisk the remaining egg with 3 tbsp water.
15. Use a pastry brush to brush the dough with a bit of the egg wash, then return the braided challah to the warm oven. Let rise for another 45 minutes (save the egg wash, you'll need it again shortly).
16. Once it has risen, paint the challah with more of the egg wash, then sprinkle with seeds, if using. Set aside (out of the oven) briefly.
17. Preheat the oven to 375.
18. Bake the challah for 30-35 minutes, or until golden-brown, and hollow-sounding when rapped gently on its bottom.
19. Let cool slightly, then serve.