If eggs come into contact with heated coils, they will fracture. To prevent the eggs from shattering, cold water should always be used. To make the egg more tender, bring the water to a boil only once and then keep the egg in the water until the bubbles cease. If you want a firmer egg, give the water a single boil, then wait two minutes, then do it two or three more times (ideally in a kettle that switches off automatically when it boils)
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