According to McDonald's
, their special sauce
is made up of the following:
Soybean oil, pickles, distilled vinegar, water, sugar, egg yolks,
high fructose corn syrup, corn syrup, mustard flour, salt,
xanthan gum, potassium sorbate as a preservative,
natural flavor (vegetable source), spice and spice extractives,
garlic*, hydrolyzed soy, corn and wheat protein, extractive of onion and paprika,
calcium disodium EDTA to protect flavor.
Plus the one secret ingredient I'm sure they left out by accident: LOVE.