Simmer the potatoes for 15 minutes until tender, then drain, let cool slightly, then quarter.
Meanwhile, put the ingredients for the dressing in a small bowl, season with a little salt & freshly ground pepper, then whisk together.
Put the potatoes into a bowl and whilst still warm pour over half of the dressing, leave to cool
Add the onion, chickpeas, tomatoes, olives & parsley, then the remaining dressing, toss together and serve at room temperature.
500g (1lb 2oz) Salad Potatoes (such as Charlotte or Maris Peer), scrubbed
2 small red onions, thinly sliced
400g can chickpeas, drained & washed
175g (6oz) cherry tomatoes, halved
50g (2oz) black olives, pitted & chopped
Small handful of flat leaved parsley, shredded
2 tbsp extra virgin olive oil
2 tbsp lemon juice
1 tsp grated lemon zest
1 tsp Dijon mustard