Mix water, yeast, and sugar in a bowl and let rest for 10 minutes.In the mixer bowl, combine buttermilk, butter, honey, and yeast mixture, and mix well.Add salt and 2 cups (240 g) of flour at once.Mix with the hook until well combined and the dough is smooth.Add the remaining flour, 1/2 cup (60 g) at a time, while mixing.Continue kneading for 5 minutes or until the dough is soft and elastic.Place the dough in a large, lightly oiled bowl, and turn the dough to coat with oil.Cover with plastic wrap and let rise at room temperature until the dough has doubled in volume, about 60-75 minutes.Punch down the dough and place it on a floured surface.Prepare two baking sheets with silicone mats or parchment paper.Divide the dough into two equal parts, then divide each part into 6 equal pieces, shaping each into a ball.For braiding, refer to the Piroulie technique, which uses 4 strands, but it’s similar for 6.Place the balls on the baking sheets and cover with a cloth.Let rise for 45 minutes or until the bread has doubled in volume.Twenty minutes before baking, preheat the oven to 375 F (190 C) and brush the bread with a brush.Sprinkle with black sesame seeds to taste.Bake for 30 minutes, or until golden brown and sounds hollow when tapped.Remove the bread from the oven and let cool on a rack before serving.