A 1970s name on a somewhat older concept.
Brittany Dressing took its name from The Brittany restaurant in Bloomington, Illinois, which was subsequently purchased by Jim’s Steakhouse of Peoria and turned into the Bloomington outpost of the Jim’s brand.
That said, dressings of this type did exist before they took on this name, typically under a name like “sweet and sour dressing.” The major difference is that, usually, they were for potato salads or warm savory salads, like a Brussels sprout salad. But there were exceptions. For example, consider this recipe from the July 28, 1926 edition of the Decatur (Illinois) Review:
By Sister Mary.
Four thin slices bacon.
Wash lettuce, crisp and dry. Shred three or four of the other leaves and combine with the beans sprinkled with onion juice. Chill, scald, peel, and chill tomatoes. Cut bacon in half-inch pieces and broil until crisp and brown.
Arrange beans and shredded lettuce on a bed of the inner leaves of lettuce and sprinkle with the crisp strips of bacon. Cut tomatoes in quarters and arrange around the bean salad mixture.
Serve with sour cream dressing made by whipping 1 cup of chilled sour cream until solid. Add tablespoon sugar, 1 teaspoon salt, 1/3 teaspoon ground ustard and 1/4 teaspoon paprika, mixed and sifted. Beat in 3 tablespoons lemon juice and 1 tablespoon vinegar and chill.
From the box of Evia Marie Sands of Louisville, Kentucky.
8 strips bacon
2-1/2 tsp. sugar
2 tsp. vinegar
8 oz. sour cream
Combine sugar, vinegar, and sour cream. Refrigerate. Fry bacon and crumble.
Add bacon and croutons to salad and top with dressing.