A few definitions are in order. To the processed- food biz, French dressing is a thin, pourable mayonnaise with a little tomato paste thrown in for color. Add chopped pickle to French dressing, and you have Thousand Island dressing. Add chopped bell pepper instead, and you have a blend of Russian dressing.
The Big Mac Secret Sauce plainly has a mayonnaise-type base. That is to say, it probably contains vegetable oil, water, vinegar, and egg yolk. Most mayonnaise also contains sugar. The Secret Sauce is the color of French dressing, but it contains chopped solids. If you scoop up a glob of the Secret Sauce and wash off the recognizable by the thin green skins adhering to white interiors. McDonald’s may claim the exact composition of the sauce to be a secret, but it appears to be well within the conventional definition of Thousand Island dressing. In fact, the color of the Secret Sauce is a dead ringer for Kraft Thousand Island Dressing. For what it’s worth, Kraft’s list of ingredients reads: “Soybean oil, water, sugar, tomato paste, chopped pickle, vinegar, egg yolk, salt, mustard, flour, propylene glycol alginate, dehydrated onion, spice, calcium disodium EDTA to protect flavor, natural flavor.”
According to McDonald’s employees, corporate policy dictates exactly where the sauce is flopped onto the sandwich. There are thirteen layers in a Big Mac, two of them being dollops of Secret Sauce. The stacking order runs as follows: top bun, onions, meat, pickles, lettuce, Secret Sauce, middle bun, onions, meat, cheese, lettuce, Secret Sauce, bottom bun.