To begin, wash and prepare potatoes. You can peel them if you like, but I usually leave most of the skin on and simply trim off any rough patches.
Cut the potatoes into 3/4 inch chunks. Place them in a large pot or Dutch oven. Fill the pot with water, to an inch above the potatoes.
Add in 1 teaspoon of the salt.
Bring the potatoes to a boil. Reduce heat to medium and simmer for 12-16 minutes, or until the potatoes are just tender.
Drain the potatoes by gently pouring them into a colander. Allow the potatoes to come to room temperature. *I speed this up by spreading the potatoes out on a baking sheet to cool.
In a large bowl, combine the remaining 1/2 teaspoon of salt along with the mayonnaise, ketchup, horseradish, spicy brown mustard, lemon juice, garlic, paprika, sugar, Worcestershire sauce, black pepper, and cayenne pepper. Whisk these together until smooth.
Stir in the onion, celery, and parsley.
Add the potatoes to the mixture and gently stir to combine.
Cover and refrigerate for 30 minutes to allow it to cool and the flavors to combine.
Enjoy!
Notes
Cooking time includes time for the potatoes to cool.