In a small bowl, mix the warm water, sugar and yeast and let it sit until it starts foaming, for about 15 minutes.
In a large bowl add the flour, egg, 1 tablespoon of the vegetable oil, salt and the yeast mixture. Mix it all together using your hands, if you find the dough too sticky just add more flour. Knead the dough on a floured surface for a few more minutes, until it becomes elastic. Alternatively, you could use a stand mixer to mix the dough.
Place the dough in a lightly oiled bowl and let it rise until doubled in size, in a warm spot. This could take 1 to 2 hours.
Cut up the pork loin in small pieces and set aside. In a medium sized bowl, add the garlic and ginger paste, 1 tablespoon of vegetable oil, honey, Hoisin sauce, soy sauce, Shaoxing wine, pepper, salt, five spice powder, and sesame oil. Whisk everything all together and add the pork to it. Let the pork marinate for about 1 hour, or until the dough is almost ready.
Heat a skillet, over medium heat and add the remaining 1 tablespoon of vegetable oil to it. Add the pork mixture including the marinade to it and cook until the pork is cooked thoroughly, for about 5 minutes. Before removing it from heat, add the green onions to it and mix well.
Preheat the oven to 350℉.
Divide the dough into 12 equal pieces. Roll each piece into a ball. Using a rolling pin, roll out each ball into a disc, so that it's about 4 or 5 inches in diameter. Place heaping tablespoon of the meat mixture in the middle of it. Seal the bun by gathering up the edges of the disc.
Place the sealed side down bun, on an ungreased baking sheet. Repeat with remaining balls and meat mixture.
Brush the buns with the beaten egg. Transfer the baking sheet to the preheated oven and bake for about 15 to 20 minutes or until the buns are nice and golden brown.