In a small saucepan, heat the gelatine, lemon juice and water to liquid consistency, do not boil.
Add mayonnaise, chopped eggs, onion, Worcestershire sauce, salt and pepper to the gelatine mixture.
Mix together and then carefully fold in the caviar.
Pour mousse into an oiled mold and then refrigerate.
Since the mixture sets up very quickly, it can be made the day it is to be used.
It is particularly effective when molded into a fish and garnished accordingly after it has been turned out onto a serving dish.
Serve with Melba toast or crackers.
Note: The combination of ingredients causes the mousse to turn green upon standing.
However, it is perfectly edible and will keep for several days under refrigeration.