Halve the large new potatoes so that they're all around the same size. Bring a large pot of water to the boil and add plenty of salt. Add the potatoes and cook for 10 minutes until soft. Drain and leave to cool.
Add the cooled potatoes to a large bowl with the cucumber. Whisk together all of the dressing ingredients with a large pinch of salt and pepper and pour over the potatoes. Toss and serve.
Nutrition information is an estimate and will vary depending on the exact ingredients used.