This is a trick. There is much salt.
Step1:*No need to wash eggs, put them directly into the fresh-keeping box. Sprinkle salt and pour water (3 / 4 of duck eggs have not been washed). *Before closing the lid of the box. Wrap a layer of plastic film, close the lid and then wrap a layer of plastic film, perfect sealing without water leakage.
Step2:Put it in the shade and forget it.. 30 days later. As soon as you knock on the shell, you pour oil out. It was a great success.
Cooking tips:There are skills in making delicious dishes.