Hard-cooked eggs are prone to greenish-colored yolks and sulfurous odors. Our tests uncovered what causes the problem and how you can make perfect hard-cooked eggs every time. Don’t boil the eggs. After countless tests, the test kitchen found it best to cover the eggs with an inch of water, bring to a boil, cover, and remove from the heat. Let stand 10 minutes. Meanwhile, fill medium bowl with 1 quart water and 1 dozen ice cubes. Pour off water from saucepan and gently shake pan back and forth to crack shells. Transfer eggs to ice water with slotted spoon and let cool 5 minutes. The gentle heat perfectly cooks the eggs—not a chance of the green tinge or unpleasant smell.
To center the yolks, turn the carton of eggs on its side in the refrigerator the day before you plan to cook the eggs.