Weigh all the seasonings and mix in a small bowl
Cut the pork into 1" thick slices
Sprinkle the mixed seasonings onto the pork slices
Move all the pork slices into the pot, add the vinegar, and rub the pork pieces with one hand
Cover the pot and let the pork marinate for 75-90 mins
Put the pot on the stove, turn the heat to high, flip the pork pieces until the juice starts to boil
Turn heat to low, keep the lid on, and simmer for 75 mins
Remove the lid, turn heat to high, to reduce juice
Set oven at 325F. Put the pork pieces onto baking pan and bake for 5-7 mins, or until the grease starts to sizzle
Change the oven setting to broil. Broil the pork on the low setting for 2-3 mins, or until the surface of the pork turns brown
Take the pork out of the oven, cut into fine pieces, add them back to the pot, and mix with the remaining juice in the pot
Slice the bun in half
Stuff the bun with pork and serve