Cut the melon in half horizontally. Take out the seeds and then scoop out the flesh with a tablespoon taking care not to spoil the green shells. Put these shells in the ice-making compartment of the refrigerator. Purée the melon flesh in a liquidiser or through the finest blade of the mouli-légumes, then strain it into a bowl through a fine sieve or strainer.
Add the lemon juice, sugar and a pinch of salt and beat thoroughly with a wire whisk to dissolve the sugar. Transfer to the ice-cream maker and freeze.
When it is ready scoop the sorbet into balls with a tablespoon dipped into hot water, and pile into the two green melon skins. You can crown each half with a strawberry.