Mayonnaise Cucumbers,peeled/sliced * squeezeed dry in paper toweling. Pour boiling water over gelatin and stir until dissolved. Add cold water, lemon and onion juice. Chill until very thick. Stir in sour cream, then fold in cucumbers and radishes. Pour into a long, shallow pan that has been very lightly oiled with mayonnaise. Chill until firm. Cut into squares in pan and lift out onto chilled serving plate. Serve with mayonnaise and garnish with slices of cucumber.