Peel the pineapple and remove all eyes. Dip the nectarine in hot water and then peel it too. Peel and fillet the orange. Cut all types of fruit into small pieces and place in a saucepan.
Bring to the boil with sugar, cassis and a few dashes of grenadine and simmer gently for about 15 minutes while stirring. Use the hand blender to carefully puree the simmering mass in the pot (risk of splashing!).
Pour hot into rinsed glasses and seal. The amount is sufficient for approx. 2 glasses of 500 ml each.