The original recipe for this dish called for half white and half green asparagus. Unfortunately, good quality white asparagus are rarely available in this area. If you want to prepare the dish ahead of time, chill the asparagus in ice water immediately after cooking to preserve their texture and color. Then drain them well and set aside until serving. At first glance, the sauce appears to be an ordinary thousand island dressing, but the crème fraîche and cognac give it a different character than one may expect.