Despatch the lobsters in the way recommended. Bring 5litres (9pints) of water with 8tablespoons of coarse salt to the boil and plunge in the lobsters. Cook at a rolling boil for 15 minutes, then remove from the heat. Leave the lobsters in the pan for a further 5 minutes. Then remove them and let them cool for 5–10 minutes.
The next stage is somewhat complicated so read the instructions carefully before you start and then read them again as you undertake each step.
(a) Remove the claws. Bend the smaller, movable pincer backwards till it comes away, bringing its cartilage with it. Crack the shell of the claw at the thickest part with the flat of a heavy knife without crushing it, in such a way that you can pull out the claw meat in one piece. Do the same with the small pincer. Put the flesh on one side and keep the pieces of shell.
(b) Separate the ‘rings’ of the tail shell by rotating them in the opposite direction from their neighbours and taking care not to break them. Extract the flesh by cutting through the underside of the tail with a pair of stout kitchen scissors.
(c) Remove all the legs, including the parts joining them to the underside of the head. Put 8 legs and one head on one side on a board.
You should now have: a plate containing the flesh of the claws and tails, a plate containing 8 legs and one whole head shell and a board containing the tail shells, the remaining legs, the parts joining all the legs to the head, the fragments of claw shell and the remaining head.
Crush the contents of the third plate, shells, legs and head, roughly with a cleaver or the back of a very large heavy knife.
Melt the butter in a saucepan and add the chopped carrot, shallot and celery. Allow to become golden over a moderate heat, then add the tomato puree. Mix carefully, and add the crushed carcases (3). Stir again and heat through for 3–4 minutes. Pour on the cognac and set it alight. When the flames have died down, add the Sauternes and reduce by half. Add the cream and the sprig of tarragon and reduce again over a moderate heat for 15 minutes. Salt lightly.
Strain the sauce through a fine wire sieve into another saucepan, pressing the lobster shells carefully with the back of a ladle to extract all the juices and cream. Taste and add a pinch of salt and pepper if necessary.
Just before serving, put the lobster flesh into the sauce and cook for a minute or two. Divide between two deep plates and decorate with the sprigs of chervil. Finish by garnishing each plate with 4 legs and half the reserved head (cut in half with scissors).
I can only recommend a Sauternes with this dish, but there is of course the problem of which wine to serve next. You could perhaps pick a Chassagne-Montrachet or a fruity Pouilly fume. You could also try one of the marvellous white Châteauneuf-du-Papes.