Put the rock lobster in the freezer for an hour or ask your fishmonger to oblige (it will deteriorate quickly, hurry home and have all the other ingredients ready).

Drop lobster into well-salted boiling water - or, better still, sea water - and simmer for 12 minutes.

Remove and cool in fresh water for five minutes.

Drain away liquid and tear tail away from head.

Pick off all the meat, including the yellow mustard and the leg and claw meat.

Extract the intestinal thread that runs down the centre of the tail and chop the tail meat into medium-sized chunks.

Stir in all the other bits of meat and mustard, cover and refrigerate.

Chop the mace very finely.

Add it to the pan with the unsalted butter and salt and pepper.

Heat until just melted and stir through the chopped crayfish meat.

Pulse in batches in a food processor for half a minute to achieve a coarse texture.

Mix everything well and taste for seasoning; cold food can take a bit more seasoning.

Pack into a china pot or pots, pressing down very well to expel air.

Pour over a half-centimetre layer of clarified butter to seal, and then refrigerate. Serve with plenty of hot toast.

To clarify butter

Heat butter in a heavy pan until the milk solids separate from the oil, the butter should bubble for a few minutes.

Ladle through a folded piece of damp muslin lining a fine sieve that is resting on a bowl.

Makes appetisers for 10-12.