Stir together instant yeast, sugar, and warm water in a large bowl and let sit for 10 min until foamy.
Add flour, baking soda, and salt and stir until dough forms. Use your hands to knead until smooth and forms into a slightly sticky ball.
Cover with a kitchen towel and let it sit for about 1 hr at room temperature until it doubles in size.
While the dough is rising, combine all ingredients for the pork filling in a bowl and mix. Place in the fridge until ready to use. Line a bamboo or a regular steamer basket with parchment paper, and poke some holes into it with a sharp knife.
Once the dough is ready, sprinkle flour on a clean surface, then knead the dough a few times. Divide the dough into 2 equal pieces, then make a log with each piece. Slice each log into 6 equal pieces, so you have 12 pieces total.
Shape a piece into a ball, then flatten it out into a circle with your hands. Add about 2 tbsp of the filling in the center, then close the outer edges to close over the filling into a ball rolling it between your hands until smooth.
Place on the prepared steamer basket, cover, and repeat with the rest of the dough and filling, leaving about 1 inch space in between the buns. If the steamer basket is full, you can place the buns on a parchment paper lined plate and cover with a kitchen towel. Keep covered for 15 min until they puff up slightly.
Boil a pot of water over high heat, then add the steamer basket inside. Steam on full boil for 15 minutes. Turn off heat, and let the buns sit for 4-5 minutes before opening the lid. Repeat with the rest of the pork buns.
Enjoy warm on its own, or with your favorite dipping sauce like chili oil or mixture of soy sauce and vinegar.