Spider crabs make the best terrine, but ordinary crabs make a very pleasant one too.
First pick the meat out of the crab, reserving all the pieces of shell.
To make the reduction, melt the butter in a pan and cook the carrot, onion and celery in it until beginning to colour. Add the crab shells, tomato, tomato purée and white wine and stir over a high heat for 2 or 3 minutes. Add the water, bring to the boil and simmer for 40 minutes. Strain through a sieve into a second saucepan. Reduce this liquid down to 2 tablespoons by rapid boiling. Allow to cool a little.
To make the terrine, bring half the cream to the boil, then take it off the heat. Whisk the egg yolk with the shellfish reduction and add the hot cream. Stir constantly with a wooden spoon over a moderate heat till the savoury custard starts to thicken. Take off the heat and add the gelatine. Cool the pan by setting it in a bowl of iced water. When it is tepid, add the crab meat and lemon juice, and season if necessary with salt and a pinch of cayenne pepper.
As the crab mixture gets colder, it will begin to set. Before it sets too hard, whip the remaining cream until thick and soft but not stiff, and fold it into the mixture. Then beat the egg white to soft peaks and fold that in too. Pour the mixture into a terrine mould oiled with groundnut or sunflower oil. Leave to chill for at least 3 hours in the refrigerator.
Turn out by inverting the mould and bringing it down on to a tray with a firm tap. Repeat until it slips out. The coating of oil should be enough to slide it out, but if it fails to move, dip the mould briefly into hot water.
Slice the terrine with a thin-bladed knife first dipped into very hot water. Accompany each serving with a quarter of avocado, peeled, sliced and dressed with an olive oil dressing, and a couple of leaves of dressed endive.
© 1988 Keith Floyd estate. All rights reserved.