Melt the butter in a pan or microwave and set aside until needed.

Put 2 inches of water in a saucepan and heat very gently so it is barely simmering.

Separate the egg whites from the egg yolks.

In a heatproof bowl, add the white wine vinegar to the egg yolks and whisk until light and frothy.

Place the bowl on top of the saucepan, make sure that the base of the bowl doesn't touch the water.

Whisk the mixture constantly as it is sitting over the simmering water until it thickens slightly. (Don't overheat or you'll end up with scrambled eggs!)

Take the mixture off the heat completely and start to whisk in the melted butter a little at a time.

Add the lemon juice bit by bit, tasting as you go, until you get the flavour you like.

Season with salt and black pepper.

Hold each asparagus spear by both ends.  Bend slightly until it snaps. Discard the cut, woody end.

Add a centimetre or so of water to the bottom of a saucepan. Insert your steamer and steam the asparagus spears with the lid on for 3-5 minutes depending on their thickness.

Remove from the steamer and serve with the hollandaise sauce.