In a large mixing bowl, combine warm water, granulated sugar, and active dry yeast. Let it sit for about 5 minutes, or until the yeast becomes foamy.
Add milk, vegetable oil, and activated charcoal powder to the yeast mixture. Mix well until the activated charcoal is evenly distributed.
Gradually add all-purpose flour and salt to the wet ingredients, stirring until a sticky dough forms.
Knead the dough on a lightly floured surface for about 10 minutes, or until it becomes smooth and elastic.
Place the dough in a lightly greased bowl, cover with a clean towel, and let it rise in a warm place for about 1-2 hours, or until it doubles in size.
Once the dough has risen, punch it down and divide it into 8 equal portions. Shape each portion into a ball and place them on a baking sheet lined with parchment paper, leaving enough space for them to expand.
Cover the shaped buns with a clean towel and let them rise for an additional 30 minutes.
Preheat the oven to 190°C (375°F).
Beat one egg and brush the surface of each bun with the beaten egg for a shiny finish.
Bake the buns in the preheated oven for 15-20 minutes, or until they are firm and sound hollow when tapped on the bottom.
Allow the buns to cool on a wire rack before serving.