Let the water, vinegar, sugar and salt simmer for about 2 minutes. Cool down and season to taste. The sauce should taste sweet and sour.
Cut the cucumber, peeled or unpeeled, into quarters lengthways, core and thinly slice the peeled shallots into fine wedges. If necessary, core the chillies and cut into thin rings.
The ingredients for the relish are only mixed together shortly before serving. Please don`t make the relish as thick as e.g., Mix the cucumber salad. The cucumber and shallot slices are welcome to swim a little in the sugar-vinegar syrup.