Step 1. Mix the ingredients for the tangzhong in a small saucepan and whisk over low heat until it thickens to a smooth paste. Let it cool for 5 minutes.

Step 2. Melt the butter and allow it to cool slightly while you prepare the rest.

Step 3. In a large mixing bowl, combine the flour, sugar, salt, yeast, cooled tangzhong, egg, milk, and melted butter. Mix by hand or with a stand mixer fitted with a dough hook.

Step 4. Knead the dough for 10 minutes until it becomes smooth, elastic, and slightly tacky but not sticky.

Step 5. Shape the dough into a ball, place it in a floured bowl, cover with plastic wrap or a clean towel, and let it rise for 45–60 minutes or until puffed up.

Step 6. Once risen, gently press the dough down to degas and release air bubbles.

Step 7. Divide the dough into 6–8 equal portions, depending on your preferred bun size. Shape each piece into a smooth, round ball.

Step 8. Place the dough balls on parchment-lined baking sheets, leaving space between each. Cover again and let them rise another 45–60 minutes until noticeably puffy.

Step 9. Preheat your oven to 350°F (175°C) while the buns are finishing their second rise.

Step 10. In a small bowl, beat one egg. Brush the tops of the buns lightly and evenly with the egg wash. Sprinkle sesame seeds or salt if desired.

Step 11. Bake the buns for 12–15 minutes or until golden brown on top and cooked through. Internal temperature should reach 200°F.

Step 12. Transfer the buns to a wire rack and let them cool for 10 minutes before serving.