Combine pork, mirin, tamari, sesame oil, 5 spice, white pepper, black pepper, salt, and monkfruit sugar in a bowl. Mix well and refrigerate for 3 hours or overnight to marinate.
Add green onion to the pork mixture when ready to start making the buns.
Preheat the oven to 400 degrees F.
Split dough into 8 equal-sized dough balls and lay them out on parchment paper or a lightly floured surface.
Flatten or roll the dough balls into 5-inch wide circles.
Spoon pork mixture into the center of each dough circle. Gather up the edges and pinch shut to form your pork bun.
Beat the egg to create an egg wash, then brush each bun.
Pour sesame seeds on parchment paper. Roll the top of each bun in the sesame seeds to make a sesame seed crust. Place buns on a baking sheet.
Bake for 20 - 25 minutes until pork is cooked through.