Famous Russian Salad - Olivier salad

The exact recipe—particularly that of the dressing—was a zealously guarded secret, but it is known that the salad contained grouse, veal tongue, caviar, lettuce, crayfish tails, capers, and smoked duck, although it is possible that the recipe was varied seasonally. The original Olivier dressing was a type of mayonnaise, made with French wine vinegar, mustard, and Provençal olive oil; its exact recipe, however, remains unknown.