Salt, pepper COVER POTATOES IN PAN with cold water and bring to boil over high heat. Cook until potatoes are tender. Meanwhile, thinly slice mushrooms, onions and celery and combine in mixing bowl. When potatoes are tender, drain and halve or quarter potatoes, depending on size and add to bowl. Sprinkle with vinegar. Cover and refrigerate. When cool, chop eggs and add to bowl. Add mustard and mayonnaise, and season to taste with salt and pepper, mixing everything together gently. MICHAEL ROBERTS PRODIGY GUEST CHEFS COOKBOOK