Lightly roast the walnuts without fat, sprinkle sugar over them and heat until they caramelize light brown.
Wash the plums thoroughly, stone them and quarter them. Mix the fruit pieces, sugar and lemon juice and cook for 4 minutes while stirring. Finally stir in the plum water and the roasted walnuts, pour into prepared glasses immediately and close immediately.
Turn it over several times as it cools so that the salt is evenly mixed.