ISO: Marshall Field's Special Salad DRESSING

The open-faced sandwich includes untoasted rye bread, iceberg lettuce, sliced turkey breast, swiss cheese, crisp bacon slices, black olives and LOTSA the Marshall Fields special dressing. There are no tomatoes. The tomato flavor (and the best part of this legendary menu item which BTW is now ONLY served in the Walnut Room of the Chicago State Street store) comes from the Russian-style salad dressing. The dilemma is that MF used to sell this salad dressing in the gourmet shops of all of their stores -- but the item was discontinued a year ago. I have written to customer service and they will not provide the recipe -- they tell me that it is bottled for them but their supplier will not give it up! If anyone has a copycat recipe for the salad dressing, I would be grateful.