Wash the rhubarb, drain and cut into small pieces. Weigh 500 g. Wash, clean, drain and quarter the strawberries. Weigh 500 g. Wash lemon balm and dab dry.
Cut leaves into fine strips. Peel limes so that the white skin is completely removed. Remove the fillets between the parting skins. Mix rhubarb and strawberries in a pot with jam sugar.
Bring to the boil while stirring and boil for 3 minutes until bubbly. Fold in lemon balm leaves and lime fillets. Pour into prepared glasses and close them.