1Dice enough of plums to measure 1/2 cup and reserve.
2Coarsely chop remaining plums and purée in 2 batches with 1 cup chilled syrup in a blender.
3Pour purée through very fine sieve into a bowl, pressing on and discarding solids.
4Stir in diced plums, lime juice, and chilled syrup to taste.
5Single cream on the top is optional