Drain the cornichons and slice into small pieces, approximately 5 mm thick.
Finely dice the onion or slice the spring onions and place them the small bowl.
Add the stock cube to the small bow and pour over boiling water until the onions are just under the water. Stir well.
Add the mayonnaise and mustard and season. If it is not creamy enough for your liking, add more mayonnaise. Stir well.
Drain the cooked potatoes and place them in the salad bowl. Add the mayonnaise and onion mix and stir through. Allow the salad to sit for a couple of hours, preferably somewhere cool, stirring regularly to ensure that all the potatoes are covered in the dressing.
Finely chop the parsley and sprinkle it over the top. Cut the eggs into quarters and lay the quarters on top to serve.