Thanks to all.
A friend of mine described his as made with mayo as “vinaigrette sauce” or more correctly to some, “A sauce made of vinegar, oil, shallots, parsley, etc., used especially on cold meats, as calf’s head.” -from Webster’s Collegiate dictionary, 1960 ed.
Also called “vinaigrette dressing” and can be used on fish.
But I was just asking, specifically, as I mentioned earlier, with fewer ingredients, so I assume it is not “vinaigrette” specifically, as was made by our family. And no salad oil, mayo, or sour cream!
I found a recipe for vinaigrette dressing in my Betty Crocker cookbook, and it asks for all kinds of stuff but only ¼ cup vinegar and ¾ cup salad oil. Other ingredients include sugar, paprika, mustard, lemon juice in place of vinegar, a few drops of onion juice or clove garlic, green olives, dill pickles, chives, pimento, and hard cooked eggs.