Eggs lowered into boiling salted water and cooked for 15 minutes, then cooled and peeled. The time is the whole recipe, and less of it gives a softer yolk.
Fifteen minutes gives a fully hard yolk, pale and crumbly all the way through, which is what this recipe is for. If you want something else, the time is the only thing to change: six minutes leaves the yolk liquid, eight gives it a jammy centre, ten sets it soft, and twelve is firm but still bright yellow. Lower them in with a spoon rather than dropping them. An egg dropped into boiling water cracks against the bottom of the pot and leaks white into the water. Cool them as soon as they come out. It stops the cooking, which is what prevents the grey-green ring forming around the yolk in an egg that has sat in its own heat, and it makes the shells come away in large pieces instead of taking the white with them. Older eggs peel more easily than very fresh ones, which is worth knowing when the shell refuses to come off in one go.