2) Peel and thinly slice the red onion.
3) Toss the cucumber, onion and salt together in a colander. Set aside to drain for 20 minutes.
4) Press the excess liquid out of the vegetables, rinse well with cold water and pat dry.
5) In a medium bowl combine the vinegar and sugar, add the cucumber mixture and toss to coat. Stir in the dill and refrigerate until required.