Asparagus is at its best when served simply, as with this classic French sauce.
20 asparagus spears, trimmed and peeled
200g unsalted butter
1 egg yolk
The juice of 1 small lemon
150ml double cream
Put the butter in a small saucepan (preferably one with a pouring lip) to melt over a low heat. Place the egg, egg yolk, lemon juice and seasoning into the bowl of a small food processor. Switch it on and allow the mixture to become very thick and pale in colour (about three or four minutes should do it).
Meanwhile, reheat the butter until it is just beginning to bubble, then remove any scum from the surface with a spoon. With the motor still running, slowly add the hot butter (it must be hot) to the egg mixture until it visibly begins to thicken. Once the butter has been exhausted and you can see a modicum of milky residue left behind, stop pouring. Tip the sauce into a roomy bowl and keep it warm.
Now, boil the asparagus in well salted water for about five minutes, or until it is tender when pierced with a sharp knife. Please don’t undercook it, as I think there is nothing worse than crunchy asparagus. Once the spears are cooked, lift them out with a slotted spoon and briefly drain them on a tea towel before placing them on a warmed serving platter.
Finally, briefly whip the cream (preferably by hand) until it is only loosely thick, so that it is just showing the shape of the spokes. Carefully fold the cream into the warm sauce using a spatula and then check the taste for a possible addition of both more lemon juice and more seasoning.