(This is more or less an addition to ElendilTheTall's answer, but it's too long to fit into a comment.)
My experience with eggs is that "let them cool afterwards" won't fully do the trick, since the egg yolk will simply continue to cook from the heat left in the egg. To prevent that, after boiling for five minutes, you need to cool them down quickly by putting them under running cold water. This stops the cooking process, and when deep-frying later on, they will just heat through, but the yolk will stay runny and not start to set anymore.
See also here in section "Cooling".
For a recipe, see here for an example. When this was broadcast (last month I think), there was a lot more emphasis in the programme on how important it was to cool the eggs than the sentence Drain and cool the eggs under cold running water suggests.