Gather Your Ingredients: Ensure you have all the ingredients measured and ready to go.
Mix the Mayo and French Dressing: In a medium-sized bowl, combine the mayonnaise and French dressing. Stir until well blended.
Add the Relish and Onion: Incorporate the sweet pickle relish and finely minced onion into the mixture. Stir to combine.
Incorporate the Vinegar and Sugar: Add the white vinegar and sugar to the bowl. Mix until the sugar is fully dissolved.
Season with Pepper: Finally, add the pepper and give the sauce one last thorough mix.
Chill and Serve: For best results, let the sauce chill in the refrigerator for at least an hour before serving. This allows the flavors to meld together beautifully.