I know this is pretty basic stuff, but I always think that the most useful thing I know about boiling eggs, is that you can prevent cracking during cooking by making a pinhole in the ‘top’ of the rounded end of the egg. Hence, a hat pin, or maybe a map pin, is an excellent piece of equipment to use when boiling an egg. You just need a very small amount of pressure to make the pinhole. I have never broken an egg when doing this.
I always use large eggs. If you want yours soft boiled then 5 minutes from being plunged into rapidly boiling water should do the trick. For hard-boiled eggs allow to boil for 12 minutes (and immediately cool them in a bowl of cold water (if serving cold)).
For other sizes, one way to ensure they are cooked is to take the egg out of the boiling water with a slotted spoon. Hold the spoon away from the pot and count how many seconds the wet egg takes to dry:
- a hard boiled egg will dry in about 8-10 seconds;
- a soft-boiled egg will dry in about 18-20 seconds.