Boil the potatoes until fork tender, about 20 minutes. Drain and allow to dry well.
Add the potatoes to a large container. Add the butter, sugar and salt, and mash to a smooth consistency with a potato masher, being careful to incorporate all the ingredients evenly. Refrigerate for several hours, until cold.
Add the mustard, relish, sandwich spread, pimentos and parsley to the potatoes and mix well. Gradually mix in the mayonnaise, taking note of the consistency and flavor as you go -- you may need to add more or less mayonnaise than the recipe calls for, depending on personal preference.
For best results, refrigerate for several hours before serving.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.
Recipe courtesy of Burns Original BBQ, Houston, TX