Wash the meat pieces under running water. Then fill a large mixing bowl with water. Let the meat pieces soak in the water for 30 minutes.
After 30 minutes, drain the residual water. And rinse-off the meat again.
Then place each meat piece in a large pot. Fill the pot with just enough water to cover the meat pieces. Bring the pot up to a boil on a high heat.
Once it starts boiling, drain out the pot. And give the boiled meat pieces one final wash under running water.
Place each cleaned, boiled meat piece back into the pot. Now fill the pot up with 25 cups of water. (If you're pot is small, reference notes.)
Then bring the pot back to boil on a high heat. Once it starts to boil, use a soup ladle and scrape off the residual scum on the surface.
Then reduce your heat to LOW (Important!). Let it gently simmer for at least 5 hours.
Note: Every 2 hours, open the lid and skim-off the residual oil.
After ~5 hours, you will end up with a rich and milky broth. And the meat will be pull-apart soft.