In a medium bowl, whisk together sour cream, mustards and pepper. Add a pinch of salt to taste. Set aside.
In a large pot, add potatoes, cover with water and bring to a boil. Turn down heat, add salt and simmer for about 30 minutes or until potatoes are tender. Drain water with a colander, setting it back into the pan to let potatoes cool well.
Place potatoes into a large serving bowl then add sour cream mixture, gently stir to blend. Cover with plastic wrap and refrigerate about two hours to set.
Serve cold and garnish with fresh chives on top. Enjoy!