Prepare the Tangzhong: In a small saucepan, combine equal parts of water and bread flour, stirring constantly over medium heat until the mixture thickens to a pudding-like consistency, about 3-5 minutes. Allow to cool.

Activate Yeast: In a mixing bowl, combine lukewarm milk, sugar, and active dry yeast. Let sit for 5-10 minutes until bubbly and frothy.

Make Dough: Add cooled tangzhong to the yeast mixture, along with dry milk powder, an egg, flour, and sea salt. Mix until a scraggly dough forms.

Knead Dough: Transfer to a floured surface or stand mixer. Knead on low speed for about 5 minutes. Add softened butter, knead for another 5-7 minutes until smooth and slightly tacky.

First Proofing: Shape into a ball, place in a greased bowl, cover, and let rise in a warm area until doubled, about 1-2 hours.

Shaping: Punch down the dough, divide into portions for rolls or a loaf. Shape and place in a greased pan.

Second Proofing: Cover and let rise again in a warm area until doubled, about 1-2 hours.

Bake: Preheat oven to 350°F (180°C). Brush with egg wash, bake loaf for 30-35 minutes or rolls for 20-30 minutes until golden brown.

Cool: Let cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.