To make the dressing, whisk the sherry vinegar and the truffle oil together.
In a medium pot, bring some water to the boil with the vinegar. Poach the eggs until soft and then strain on a paper towel.
Dress the rocket in some of the dressing and season.
On a plate, build up a nest of the rocket, Prosciutto di San Daniele and Grana Padano shavings. Place the egg on top, and finish with a good twist of black pepper on top and a pinch of sea salt.