Prepare a large bowl of ice water and set to one side. Put water in a large saucepan and bring to a boil. Place the fruit in the boiling water for about a minute. Use a slotted spoon to transfer the blanched fruit to the bowl of ice water. Remove when cool, this takes about a minute and then use your fingers or a paring knife to peel the skin off the fruit.
Pit the stone fruit (peaches and apricots) and then cut into chunks. Put the fruits in a blender and blitz until smooth.
Pour the fruit puree into a saucepan and add water and sugar. Cook over medium heath, stirring occasionally until the puree has reduced.
Chill the fruit puree. When you are ready to serve, add ice, the fruit puree, lemon juice and sparkling water. Give it a stir and serve.