Lobster and Chicken Sausage with Spring Onion Purée

• 1 X 655 g/1½ lb live lobster
• 1.21 litres/2

To make the mousseline, chop up the chicken breasts into small pieces, place these in a blender or food processor with the salt, and blend until it is a smooth paste. Add the egg white and process again until it stiffens. Rub the mixture through a sieve into a bowl set on crushed ice. Gradually add two-thirds of the cream, mix in well, then add the sherry and season with a litt