The greenish ring is the result of a simple chemical reaction.
When eggs are overcooked, the iron in the yolkreacts with the sulfur in the white, forming a thin layer of iron sulfide.
It’s completely safe to eat, but not exactly pretty on your plate.
The key to preventing this is temperature control.
Avoid boiling your eggs for too long. Instead, bring water to a boil, add the eggs, and then simmer—
not boil—for about 9 to 12 minutes, depending on size.
