Cut off the ends of the cucumber and peel the cucumber lengthways (organic cucumbers can be left unpeeled).
Finely slice the cucumber and place in a bowl. Sprinkle with a little salt and let rest for 15 minutes, then drain.
Peel, core and dice the tomato. Slice the onion into thin rings. Core the chilli and chop very finely.
Add tomatoes, onions and chilli to the cucumber. Whisk vinegar, sugar and a pinch of salt, as well as sambal oelek, depending on your personal resistance to heat.
Pour this dressing over the salad, stir and refrigerate for a while. Mix well before serving.
Tip: If you don`t like it that fiery, just leave out Sambal Oelek.