Skin, core and chop the nectarines. Peel the mango, remove the core and cut into small pieces. The fruits should add up to around 500g (better a little more than less).
Put the nectarines, mango, lemon juice, sparkling wine and preserving sugar in a saucepan and puree with the hand blender until there are still (very) small pieces of fruit.
Bring to the boil for 5-10 min while stirring. Pour into rinsed, cleaned glasses while still hot. Makes about 4x 200ml glasses.
PS: Can also be tried with chopped lemon balm as an addition just before filling.