Simmer the quinoa in the water for about 10 minutes until the water has been completely absorbed and allow to cool.
Dice the cucumber and tomatoes, chop the rocket and mix everything with the quinoa.
For the dressing, rub the peel of the lime into the yogurt, squeeze the lime and stir in the juice, add the olive oil and season the dressing with mustard, salt and pepper.
Pour the dressing over the salad and mix everything well.