I have found New Orleans Recipes, a great old cookbook by Mary Moore Bremer. The book I have is the Tenth Edition published in 1944. Unlike most modern cookbooks, this one presents its recipes in a simple way that encourages intuitive cooking. Here is Bremer’s recipe for Shrimp Arnaud.
Six tablespoons of olive oil, two tablespoons of vinegar and one tablespoon of paprika, one half teaspoon of white pepper, one half teaspoon of salt, four tablespoons of Creole mustard, on half heart of celery, chopped fine, one half white onion, chopped fine, and a little chopped parsley.
Mix well. Chill; Serve on cold boiled shrimp, about twelve to a serving.
Enthrone on crisp, chopped lettuce.