Why do we observe a greenish ring around the yolk of hard-boiled eggs

Their practicality makes them invaluable allies in the kitchen. You can:

Chop them up to enrich a mixed salad.
prepare homemade deviled eggs,
Place them sliced ​​on avocado toast.
slip them into a sandwich or a wrap.
With a few simple adjustments, your hard-boiled eggs will finally retain a bright yolk and a delicious flavor, every time you cook them.