- 1 egg yolk
- 1/4 cup Creole mustard (preferably Zatarain's), or other whole grain mustard
- 2 1/2 tablespoons red wine vinegar
- 1 tablespoon prepared horseradish
- 1 teaspoon kosher salt
- 1/2 teaspoon cayenne
- 1/4 teaspoon freshly ground black pepper
- 1 clove garlic, minced
- 3/4 cup vegetable oil
- 1/4 cup olive oil
- 1/2 cup finely minced celery
- 1/2 cup minced green onions (white and green parts)
- 1/4 cup mayonnaise
- 1/4 teaspoon Worcestershire sauce
In a nonreactive mixing bowl, whisk together the egg yolk, mustard, vinegar, horseradish, 3/4 teaspoon of the kosher salt, cayenne, and black pepper. On a cutting board, mash the garlic to a paste with the remaining 1/4 teaspoon of kosher salt using the side of a chef's knife. Add the garlic paste to the bowl and whisk to combine.
Combine the oils in a measuring cup with a pour spout and while whising continuously, drizzle the oil blend very slowly into the mustard mixture until a smooth, thick emulsion is formed. Whisk in the celery, green onion, mayonnaise, and Worcestershire sauce and chill thoroughly before using, up to 2 days in advance.