It is a difficult question to answer, why this topping is called Italian salad, in Piemonte a similar recipe is called Russian salad. Most food historians believe it is a reference to a European tradition of mixing mayonnaise with vegetables. A former chef colleague of mine would always mention this piece of smørrebrød as her favourite, and it has to be the classic, no twist and turns, so if I omit the recipe, I would disappoint her. Anyway, the Italian salad has to be homemade.