Hard core will appear if the curing process is not mastered well. The following introduces the practice of salted egg yolk for reference. First of all, prepare the materials: the right amount of eggs, the right amount of salt and the right amount of water.

1. Take a flat-bottomed basin that can be covered and sprinkle a layer of refined salt on the bottom of the basin.

2. Take out the egg and separate the egg white from the yolk.

3. Put the yolk on the refined salt.

4. After the egg yolk is put away, sprinkle a layer of salt on the egg yolk.

5. Sprinkle a little water on the refined salt, then cover it and put the salted egg yolk in the refrigerator.

6. Take the salted egg yolk out of the refrigerator after two days and one night.

7. Wash away the salt on the surface of the egg yolk with water.

8. done.