Bring water and rock salt to a boil; cool.
Place eggs in a crock or glass jar.
Pour salt-water mixture over eggs to cover.
Cover crock and let stand in a cool place (not refrigerator) for three weeks.
Remove eggs from salt bath and store them in the refrigerator if not ready to use immediately.
Yolks should be a bright yellow-orange color and quite firm.
The white should be slightly cloudy and still runny.
Eggs without a firm yolk should be discarded.
To hard cook, cover with fresh cold water and simmer for 20 minutes.
Shell an quarter.
Serve with hot rice or congee.
Make 12 salted eggs.
NOTE: Salted duck eggs may be purchased in mud-pack form or in brine in Oriental markets.
If in mud pack, scrape off mud, wash well and proceed with recipe.