Ever seen a green ring around your hard-boiled egg yolk? It’s not dangerous, just unappetizing. The cause? A harmless chemical reaction between iron in the yolk and sulfur in the white due to overcooking. “The end outcome is a little layer of iron sulfide,” the article explains.

Here’s how to make perfect hard-boiled eggs:

**Start Cold**
Place eggs in a pot and cover with cold water (3–5 cm above eggs). Don’t crowd them.

**Boil, Then Rest**
Heat on medium. Once boiling, turn off the heat. Cover and let sit 9–12 minutes—9 for softer yolks, 12 for firmer ones.

**Cool Fast**
Transfer eggs immediately to ice water. This stops cooking, prevents the green ring, and helps with peeling.

**Peel Easily**
After 5 minutes in cold water, peel under running water to loosen the shell.

**Extra Tips**

* Use slightly older eggs (5–7 days old) for easier peeling.
* Add salt or vinegar to water to prevent cracking.
* Store unpeeled eggs up to a week; peeled, use within 2–3 days.

The secret? “Just the ideal timing.” Avoid overcooking, cool fast—and enjoy eggs that look as good as they taste.