In a large bowl, whisk together the mayonnaise, yogurt, Dijon, vinegar, sugar, and celery salt. Stir in the broccoli slaw until well coated. Taste and add salt and pepper, as desired. Cover and refrigerate for at least 4 hours before serving.
Notes
Broccoli slaw is a mixture of shredded broccoli stalks, carrots, and red cabbage that can be found in a bag in the produce section of your grocery store. Alternatively, you may use shredded cabbage or regular coleslaw mix instead.
This quantity is enough to serve as a sandwich topping with 4 pounds of pulled pork. When I make this recipe for my family of five to eat, I cut it in half.