I use this potato salad all the time for barbecues and picnics. It can be served warm or cold. Cornichons are pickled baby cucumbers found in the condiments aisle at the supermarket. They can be replaced with sliced gherkins.
Boil or steam the potatoes for 6-8 minutes or until tender. Drain.
Meanwhile, combine the cornichons, capers and parsley in a large bowl. Whisk the oil, vinegar and mustard in a small bowl until combined. Season with salt and pepper.
Add the warm potatoes to the cornichons mixture. Drizzle with the dressing. Toss gently to combine. Serve