"Why this recipe works:We use a quality blue cheese—English Stilton—to make the rich dressing the star of this salad. Mayo and sour cream add tang and creaminess, red wine vinegar brightens it up, and a splash of milk smoothes it out to the perfect consistency—all the better to coat a crunchy wedge of iceberg. Tests proved that raw onion overpowered even our robust dressing, but shallots soaked in vinegar (which we then used in the dressing) provided a mellower onion flavor...."