Why is the yolk of my hard-boiled egg turning green?

1. Always start with cold

Place your eggs in a saucepan and cover them with 3 to 5 cm of cold water. This trick prevents thermal shock and cracked shells.

2. Heat over medium heat

Let the water heat gently until it boils. As soon as the bubbles rise clearly,  turn off the heat .

3. Let it rest, without boiling it further.

Cover the pan and let the eggs enjoy the gentle heat:

9 minutes for a slightly creamy yolk.

12 minutes for a firm yolk.