Activate the Yeast - In the bowl of a stand mixer, combine lukewarm water, sugar, and active dry yeast. Let sit for 2–3 minutes until it begins to bloom. If using instant yeast, you can skip this step.
Mix the Dough - Add bread flour to the mixing bowl, then sprinkle salt on top of the flour, not directly onto the yeast. Begin mixing on low speed using a dough hook. Once the dough starts to come together and hydration looks correct, add softened butter gradually once dough forms a ball. You will know the dough is hydrated when it starts to form a ball on the dough hook.
Knead and Test - Continue mixing until a smooth dough forms. Perform a windowpane test by stretching a small piece of dough. If it stretches thin without tearing, the dough is properly kneaded.
First Rise - Shape the dough into a tight ball and place it into a large bowl lightly lined with softened butter. Cover with plastic wrap and allow to rise in a warm place until doubled in size, about 30–60 minutes depending on room temperature.
Divide and Shape - Turn the dough out onto a clean work surface without flour. Using a kitchen scale, divide the dough into equal pieces, about 2.5-3 ounces each. Pre-shape into dough balls, allow them to rest briefly, then roll into tight, smooth rounds, building surface tension against the table.
Prepare the Baking Soda Bath & Boil Buns - Preheat oven to 375°F (190°C) to prepare for baking. Bring 2 quarts (8 cups) of water and baking soda to a gentle boil. Working in small batches (around 2 balls at a time), lower the dough balls into the boiling water using a slotted spoon. Boil for 20-30 seconds on each side, then remove and place on a wire rack to drain excess water.
Egg Wash and Score - Transfer the buns to a parchment-lined baking sheet set on a sheet pan or cooling rack. (In class, Chef Joy used and recommended a perforated baking mat to allow even air-flow under the buns). Brush lightly with egg wash using a pastry brush, then score the top of each bun with a sharp knife, scissors, or razor blade to allow steam to escape.
Bake - Bake at 375°F (190°C) for 15-20 minutes, rotating the pan halfway through, until the buns are evenly golden brown. Allow the buns to cool slightly before serving. Enjoy!