Bloom the yeast: In a large mixing bowl, stir the warm water and active dry yeast together and let stand until foamy, 5–10 minutes.
Enrich the liquid: Whisk in the granulated sugar, eggs, honey, and vegetable oil until smooth, about 1 minute.
Make the dough: Add the bread flour and fine sea salt in 2–3 additions, mixing with a spoon or dough hook until a shaggy dough forms, 3–5 minutes. The dough should be soft and slightly tacky; add only as much of the flour as needed to achieve this texture.
Knead: Turn the dough onto a clean surface and knead until smooth and elastic, 8–10 minutes. If very sticky, knead in small pinches of the measured flour until it just stops clinging to your hands.
First rise: Place the dough in the bowl, cover tightly, and let rise at warm room temperature until doubled in size, 60–90 minutes (an indentation from a fingertip should slowly spring back but remain visible).
Shape the braid: Gently deflate the dough and divide into 3 equal pieces, 1–2 minutes. Roll each piece into a 16–18 inch rope, 3–5 minutes. Pinch ropes together at one end and braid firmly to the other end, then pinch and tuck ends under for a neat loaf, 3–5 minutes.
Second rise: Transfer the braid to a parchment-lined baking sheet, cover loosely, and proof until noticeably puffy and jiggly, 45–75 minutes (the loaf should hold a gentle poke without collapsing).
Egg wash and toppings: Preheat the oven to 350°F during the last 20 minutes of proofing. Beat the egg with 1 tablespoon water until smooth, 30 seconds, then brush the loaf all over. Sprinkle sesame seeds (if using) or poppy seeds (if using) evenly on top.
Bake: Bake at 350°F until deep golden brown and the center registers 190–195°F, 25–35 minutes. If browning too quickly, tent loosely with foil after 20 minutes.
Cool: Transfer to a wire rack and cool until barely warm before slicing to set the crumb, at least 45 minutes.