This salad has much more than an assortment of flavors and textures. The beans and eggs can be cooked ahead, while the vinaigrette can be made several days in advance, leaving assembly of the salad for the last minute. It's lovely for lunch or as the anchor to dinner. Dress the beans in advance of eating to absorb the flavors of the vinaigrette.
Croque Monsieur is essentially a toasted cheese and ham sandwich. Put a fried egg on top and you've got a Croque Madame (the egg is supposed to resemble a lady's hat). What makes the difference between a toasted cheese and ham sandwich and a Croque Monsieur is the cheese – in a Croque Monsieur it comes in the form of a creamy cheese sauce. And boy, does this make a difference!