Chop the onion very finely. Mix the yoghurt with the herbs, vinegar and oil well and add a little water if you like. I prefer it when the dressing is a little more liquid. Add the onions and let the dressing rest a little so that the flavor of the herbs can develop.
In the meantime, wash the cucumber and cut it into very fine slices. The best way to do this is with a plane. Season the dressing with salt and pepper and mix with the cucumber.
I like to eat the salad as a small meal before university or during my lunch break with some rice.