Here’s something everyone needs to know: How to boil an egg correctly.
NOTE: You can also add some vinegar to the water to make the eggs easier to peel.
1. Place eggs in a saucepan with enough COLD tap water to cover completely by 1 inch. Bring to a ROLLING boil over HIGH heat. Once the water is brought to a rolling boil, PROMPTLY reduce heat to a lower medium boil and cook an additional 10 minutes for a “hard boiled” egg. For a “soft boiled” egg reduce the time by a few minutes.
2. Remove from heat and IMMEDIATELY place eggs under ice cold water or in a bowl of ICED water to chill promptly to help yolks stay bright yellow. Chill for a few minutes in the cold water until the egg is completely cooled. This is an extremely important step which prevents the greenish “ring” from forming on the surface of the yolk over time. If the egg is not chilled immediately after cooking, an unsightly dark greenish ring will eventually appear on the outside of the yolk.
3. To peel: crack on all sides, roll egg between hands to loosen shell,and remove shell. Enjoy, with a light sprinkling of salt if desired.
To serve in egg cup, place egg in cup small end down, slice off large end of egg with knife or egg scissors and eat from shell with spoon.
Refrigeration is necessary for hard boiled eggs if they are not to be consumed within a few hours.
Refrigerated boiled eggs, kept in the shell, can be kept for up to 1 week.
source: GoodEgg.com – Boiled Eggs