I’ve never read Saint Delia’s ‘How to boil an egg’, so I may be missing a trick or two. There is no precise science to the process, because apart from variant sizes, eggs take longer to cook the fresher they are.
It’s pretty impossible to know how fresh your eggs are without cracking one open, but the minute you crack one from the box into a pan for frying, it’s pretty easy to tell – if all the white of the egg spreads really thinly across the frying pan, it’s not so fresh, but if there is a discernable ring of the white that looks like clear wobbly jelly around the yolk, then it’s fresh – the higher the proportion of jelly-ness to watery-ness, the fresher it is….and all the eggs in one box should be of the same order of freshness.
If you are cooking hard boiled eggs that you’re going cut in half/slice, you should try to use the freshest eggs possible, cos the jelly-ish-ness will keep the yolk in the dead centre as it cooks – if the white has turned watery, the yolk will sink, and it’ll be lop-sided when you cut it open.
To reduce the risk of cracking, always start with eggs at room temperature. Use as small a pan as possible, so they don’t go bouncing around when the water is boiling
( you can turn down the heat to a more gentle rolling boiling once it’s got there). Add eggs to cold water or when it is just warming up, making sure the water covers the eggs entirely and start to time the eggs from when the water boils.
Rough times from point of boiling:
Soft boiled (soft whites, liquid yolks) – small 2 ½ to 3 mins, medium 3 to 3 ½ mins and large 3 to 4 mins.
Medium boiled (firm whites, soft yolks) – small 3 ½ to 4 mins, medium 4 to 4 ½ mins, large 5 mins.
Hard boiled (firm whites and yolks) – small 6 mins, medium 7 mins, large 8 to 10 mins.
If you are unsure, switch off the heat and leave eggs to stand in the water for a minute or two more.
With hardboiled eggs, take out of the water, crack the shell and immerse in cold water until cooled – this helps the shell to come away cleanly when you peel them and stops the dark, greyish ring forming around the yolk.