Place the berries, sugar and cordial in a saucepan and cook over a low heat, stirring, until the sugar has dissolved. Simmer for 4–5 minutes until the berries have softened, but still retain their shape.
To make the floating islands, fill a large frying pan with water and bring to a simmer. Whisk the egg whites and salt in a clean bowl with a hand-held electric whisk until they form soft peaks, then gradually whisk in the sugar until the mixture is thick and glossy.
Drop 6 heaped tablespoons of the meringue mixture into the simmering water, using a spoon to help it slide off. Turn after 30 seconds using a slotted spoon and cook for another 30 seconds. Remove and drain on kitchen paper.
Spoon the warm berries and the juice into 6 serving bowls and float a meringue on top.