Sweet Bun Dough

Combine milk and sugar in a large mixing container until the sugar is fully incorporated. Stir in yeast, allowing it to blend with the milk mixture for about 10 minutes, or until a creamy layer forms on top. Add flour, reserving about 1 tablespoon of beaten eggs in a small container for later use; also incorporate vegetable oil and salt into the mixture, ensuring everything is well combined.

Transfer the dough to a surface dusted with flour and knead until it becomes smooth and elastic, taking about 10 minutes to achieve this. The dough should still be slightly sticky at this point. Place the dough in an oiled large bowl, cover it with a damp cloth or plastic wrap, and position the bowl in a warm location. Allow the dough to rise until it has doubled in size, taking about 2 to 3 hours.

Prepare a baking sheet by lining it with parchment paper. Remove the dough from the bowl and give it a brief kneading session to release any air bubbles, about 1 minute. Roll the dough out into a rope and divide it into 12 equal pieces. Shape each piece into a ball and then flatten it slightly using your fingers, aiming for a disk about 5 to 6 inches in diameter.

Place about 2 tablespoons of your preferred bun filling in the center of each dough circle and fold the edges over the filling to seal it inside. Make sure there are no gaps in the dough by pinching and twisting the top together. Place each sealed bun seam-side down on the prepared parchment paper, completing the rest of the buns in a similar manner. Cover the filled buns with plastic wrap and allow them to rise for 30 minutes.

Preheat your oven to 350 degrees F (175 degrees C). In a small bowl, whisk the reserved beaten egg with water until combined. Brush the top of each bun with this egg wash and sprinkle a few sesame seeds on top.

Bake the buns in the preheated oven for 20 to 30 minutes, or until the tops are golden brown and shiny. Rotate the baking sheet halfway through the baking time to ensure even cooking. Serve the warm buns immediately.