Plunge the live crab into boiling, salted water and cook for 15 minutes. Remove from the pan and place the crab on its back. Twist off the claws and legs, crack the shell of each one carefully and extract all the flesh. Open up the crab by first pulling off the tail from the underside and throwing away. Slide the point of a knife between the shell and body, loosen and ease it out, set aside. Scrape out the flesh from the inside but discard the abdominal sac just behind the mouth. Remove the soft gills from around the body, cut in half down the middle and extract all the flesh from the cavities and leg sockets. Discard all the shell and unusable flesh.
Mix the brown meat with the mayonnaise, chives and parsley. Season with a little Worcestershire sauce and pepper to taste.
Arrange the salad leaves on the plates. Divide the brown crabmeat between the plates and surround with small piles of white crabmeat.
Stone and peel the avocados and fan by slicing very thinly from top to bottom. Arrange on the plates then dress the salads with a thin thread of vinaigrette. Serve with a sauceboat of mayonnaise flavoured with Dijon mustard.
© 1989 Kit Chapman. All rights reserved.