Place pork chops in a stockpot and pour in enough water to cover. Bring water to a boil. Remove from heat and rinse any residue on pork chops with cold water.
Return pork chops to stockpot and pour in enough cold water to take up twice the space as the pork chops. Bring water to a boil; reduce heat to low, cover, and simmer for 3 hours.
Place dates in a bowl and pour in enough water to cover; soak for 5 minutes. Drain.
Stir dates and ginger into the stockpot; add watercress and fish balls and simmer for 10 minutes. Skim off any scum from the top of the soup; season with salt.
