In a medium bowl, add the oil, lime juice, lime zest, sugar, salt and pepper. Whisk until well blended.
Wash and dry the cucumber. Using a vegetable peeler, peel the cucumber giving it a striped effect. You can also use a fork to give the cucumber smaller lines down the skin. Cut the cucumber in half lengthwise.
Scoop out the seeds. Cut the cucumber in 1/4 inch pieces and add to the bowl of dressing.
Cut the cherry tomatoes in half and add to the bowl.
Chop the red onion small and add it to the bowl with everything else.
Once all the ingredients are in the bowl, toss very well making sure that the cucumber and tomatoes are completely covered in dressing. Add the cilantro and give it another good stir. Put the salad in the refrigerator for at least 1 hour. The longer this salad sits, the better it gets. Enjoy.