1. Boil the big bones of pigs.
2. Soak the kelp knots in advance and wash them off. Put it in a soup pot, add ginger and boil.
3. Add the big bones when the stockpot water has warmed up. And add a few drops of vinegar.
4. Let it sit for an hour and add salt to the boiling pot.
Tips:Women who love beauty can put a few more slices of ginger.
