In a large bowl, whisk together the warm water and active dry yeast until foamy, 1 to 2 minutes.
Add the eggs and olive oil, stirring to combine. Then add the honey and kosher salt, mixing to combine.
Add the bread flour and mix well until a shaggy dough forms, then knead for at least 10 minutes, until super smooth.
In the same large bowl, add the dough, cover, and let it proof in a warm spot for 2 hours, until doubled in size.
Divide the dough into 2 even loaves, and each loaf into 4 balls.
Roll each piece into a long, even rope, around 18 to 20 inches long. Use flour as needed on the dough and your hands if it feels too sticky.
Arrange the 4 ropes in a cross shape: 2 ropes horizontally and 2 ropes vertically, with the horizontal ropes positioned on top of the vertical ropes. Start the braid by taking one of the vertical ropes and placing it under the left side of the horizontal rope. Then take the right side of the vertical rope and place it over the horizontal rope.
Next, take the bottom-left rope and place it over the right rope; then take the middle-right rope and place it over the vertical top-right rope. You will basically repeat this pattern until a full round is formed. Then, switch counter-clockwise and repeat.
Don't pull the strands super tight; just gently until even. When the end of the circle is done, pinch the ends together and flip the whole round challah upside down.
Place each round loaf (after it's been flipped) on a parchment-lined baking sheet. Brush with egg wash, cover loosely, and let proof again for 2 hours.
Preheat the oven to 350°F. Brush the loaves with egg wash for a second time. Top with sesame seeds, flaky salt, and poppy seeds.
Bake for 25 to 30 minutes, until deep golden brown, flipping halfway. The internal temperature should read about 190°F to 200°F.
Cool on a wire rack for at least 30 minutes before slicing.
Notes
Double egg-wash: We are adding two egg washes, for the second proof and then for cooking. This really allows the final glaze to look bright and glossy and hold its gloss after cooking. We are also doing 1 egg and 1 egg yolk, creating an even more glossy, deeply eggy finish on the challah.
Prep: You can prepare this ahead of time and serve when ready to eat, at least 1 day ahead, but on the day of is best for optimal freshness.
Storing: Store at room temperature, wrapped in an airtight bag for 2 to 3 days.
Leftover ideas: Use any leftover, day-old challah to make French toast or bread pudding! Even challah bread croutons will work great.