Make the pork bone broth the day before making this soup. Add the pork bones to a large bowl and rinse well. Fill the bowl with cold water to cover the pork bones and add the vinegar. Let sit for 20 minutes.
Drain the water from the pork bones and rinse well under cold water. Add the pork bones to a large stockpot and add enough water to cover the pork bones. Bring to a boil over high heat. Once boiling, simmer uncovered for 15 minutes.
Drain the pork bones and water into a colander in the sink. You want to discard all of the water as it is full of impurities. Also, wash the pot out to remove any impurities from that as well.
Rinse each pork bone under cold water scraping off any fat, sinue, or blood that is on the bones. This is tedious, but it will leave you with a clear stock.
Once the pork bones have been rinsed, add them back to your clean stock pot and cover with water again. Add the scallion, ginger, salt and peppercorns to the pot.
Bring the contents of the pot just to a boil over high heat. Do not bring it rolling boil. Once the water just beings bubbling, cover and reduce the heat to low. Simmer on the lowest heat setting for 12-24 hours and top off with extra water if the pork bones begin to pop out of the water. Do not stir the soup while it's cooking.
Once the soup has cooked, use a ladle to scoop out the broth into containers or another soup pot. Try not to mix the soup too much as any additional impurities are at the bottom of the pot and you don't want those in your bone broth. Discard all the bones and vegetables and you have a yummy pork bone broth!