Potato Salad (Barefoot Contessa) Ina Garten - cooking recipe

Ingredients

3 lbs small white potatoes (skins on)
kosher salt
1 cup mayonnaise
1/4 cup buttermilk
2 tablespoons Dijon mustard
2 tablespoons whole grain mustard
1/2 cup chopped fresh dill (if using dill, taste your salad for correct seasoning) or 1/2 cup chopped parsley (if using dill, taste your salad for correct seasoning)
fresh ground black pepper
1/2 cup chopped celery
1/2 cup chopped red onion
1 pinch crushed red pepper flakes (optional)

Preparation

Place potatoes and 2 tablespoons of salt in large pot of water. Bring the water to a boil, then lower the heat and simmer 10-15 minutes, until the potatoes are barely tender when pierced with a knife *.(See recipe update introduction.).
Drain the potatoes (skins on) in a colander, then place the colander with the potatoes over the empty pot and cover with a clean, dry kitchen towel.
Allow the potatoes to steam for 15-20 minutes.
Meanwhile, in a small bowl, whisk together the mayonnaise, buttermilk, Dijon mustard, whole grain mustard, dill or parsley, 1 teaspoon of salt, 1 teaspoon of black pepper, and a pinch of crushed red pepper, if using.
Set aside.
When the potatoes are cool enough to handle, cut them in quarters or in half, depending on their size.
Place the cut potatoes in a large bowl. While the potatoes are still warm, pour enough dressing over them to moisten.
Add the celery and red onion, 2 teaspoons of salt and 1 teaspoon of pepper. Toss well, cover, and refrigerate a few hours to allow the flavors to blend **.(See recipe update - introduction).
Serve either cold or at room temperature.