Boil the potatoes until soft. Drain and allow to cool.
For the sauce: Mix all the ingredients (apart from the onion and pepper) together.
Cover and place in the fridge for an hour or so (or at least until the potatoes have cooled).
In a large bowl, combine the potatoes with the onions and red pepper, then pour the sauce over.
Stir well until everything is evenly distributed.
Sprinkle with a little fresh herbs and serve with grilled chicken or any other meat.