Soften gelatine in cold water; dissolve in boiling water. Pour a little clear
gelatine in the bottom of a mold, arrange shrimp in it and chill until firm. (Shrimp
may be marinated in French dressing for a few hours beforehand, then drained well.)
Mash avocado with lemon juice; add seasonings and remaining gelatine and pour
mixture on top of firm shrimp layer.
Chill until firm.
Unmold on serving dish and garnish with lettuce, tomato and cucumber wedges.