Rinse the crab in fresh cold water. Using a large heavy knife or cleaver and one swift blow, cut the crab in two through the middle of its body between the eyes and parallel with its legs. Break the legs away from the body, remove the dead men’s fingers and discard; everything else can be used, juices as well. Leave the claws and the arms of the crab whole, but break everything else up into small pieces. Wash, peel and roughly chop the vegetables and cut the garlic into small pieces. Heat the oil in an ovenproof pan, add the vegetables and garlic, cover with a lid and sweat until they start to go soft. Add the crab, cover and sweat for about 5 minutes, stirring occasionally to prevent burning. Sprinkle the flour over the contents of the pan, but do not stir in, then place the pan in the oven for 10 minutes to singe the flour. Dot the tomato purée across the top of the flour but do not stir in. Place the pan back in the oven for a further 5 minutes to singe the tomato purée. Turn the
After 3 hours strain the soup through a sieve, pressing with the back of a spoon to ensure that every drop is drained.