Boiling an egg is considered a basic skill for even a novice cook, but it can actually be quite complex. Various problems crop up with hard-boiling eggs, from flat ends to cracked shells. Vinegar is a mainstay in most kitchens, and knowing how to use vinegar can simplify your hard-boiled egg preparation. The acid in any basic vinegar, such as apple cider or white, causes a chemical reaction with the egg that helps prevent cracks while the egg is cooking. If cracks do occur, the vinegar in the water thickens the white of the egg and reduces the egg spill.
Fill a large saucepan with water. It needs to be large enough to allow for displacement of water when the eggs are added. Fill it not more than half-full.
Add 1 tbsp. of vinegar to the water, place it on the stove top and bring to a boil. If you plan to boil a dozen or more eggs, add 2 tbsp. of vinegar.
Carefully add the eggs to the boiling water. The eggs should be covered with water when all are in the pan. Boil for 15 to 20 minutes, then remove from the heat and run cold water into the pan until the hot water is displaced. Let the eggs cool before peeling.
It is possible to start the eggs in cold water, but it tends to make them harder to peel. Vinegar can be added to already boiling eggs if it appears some are cracked. Adding vinegar to the water also help the eggs turn out round rather than flat on one end.