Bring a large pot of salted water to a boil. Blanch asparagus just until tender, about 1 minute. Plunge into a bowl of cold water to cool. Drain asparagus and place in a bowl or container. Pour on vinaigrette and cover or seal the bowl or container. Refrigerate at least 3 hours, stirring occasionally.
Just before serving, drain asparagus, reserving vinaigrette. Arrange on a serving platter and sprinkle with lemon zest, parsley, salt and pepper. Serve reserved vinaigrette in a small dish or jug on the side.