In a large pot, cover the potatoes with water. Add the Knorr Vegetable Stock Pot and cook potatoes al dente. Drain, reserving ½ cup of cooking liquid. Cool slightly and cut potatoes into cubes. Add the margarine.
Mix together the reserved liquid, mayonnaise, capers and Maille Dijon Mustard. Season with Robertsons Ground Black Pepper. Add dressing to the potatoes, and combine well.
To serve, top potato salad with the boiled eggs, chopped spring onions and parsley.