In a large bowl, whisk together all of the brine ingredients and set aside.
Place the potatoes in a large pot and cover with water. Bring the potatoes to a boil and cook until almost fork tender.
Drain the potatoes and run under cold water to cool them enough to handle. Peel the potatoes and chop into smaller pieces then slice them into ⅛-inch or thinner pieces. You can use a mandoline for this process.
Place the potatoes in a flat baking dish then pour the brine on top. Cover with plastic wrap and refrigerate overnight or for even better flavor wait 2 days. Halfway through the refrigeration process mix the potatoes to evenly coat them with the brine.
The next day, drain the potatoes of excess brine.
Place the potatoes into a bowl and mix with ¾ cup of mayonnaise to start. Add more mayo until a smooth creamy consistency has been achieved. Taste test and season with a bit more salt and pepper if required, but you shouldn't need much. Garnish with carrot and parsley. Enjoy!
