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French dressing is a term originally used for any oil-and-vinegar-based salad dressing. Today, it refers to a creamy ketchup-based dressing which varies in color from pale orange to bright red. It can be made by blending olive oil, vinegar, tomato paste, ketchup, brown sugar, paprika, and salt. In the United States during the 1950s, manufactured "French dressing" was developed. The manufactured version is sweet in taste and colored orange-to-red from the use of paprika and tomatoes. In manufactured versions, "French dressing" is generally a pale orange and creamy, while "Catalina French dressing" is generally bright red and less creamy in nature.
Video French dressing
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Source of the article : Wikipedia