Several year ago my godmother was the first person I had ever seen put Radishes in Potato Salad. Not only was it delicious but it was colorful. She was a wonderful cook and so kind to me. She had two sons so I was the daughter she never had. Many of my good memories was time spent at their home. Her husband, my god father, had such a great sense of humor,loved football and always pulling a joke on someone. It was such fun to be in their company. She worked but made large containers of this potato salad. We enjoyed it for several days. Hope you enjoy it too. Soon the sun will be shinning, the birds singing and grills cooking hot dogs and hamburgers. That's picnic time. She loved it. Her name was Agnes McMinn.
Place potatoes unpeeled and whole in a large sauce pot with one tablespoon of salt. Bring water to boil then lower heat with lid on to a low boil.After 15 minutes begin checking for potatoes to be slightly tender with a fork. You can push in with a little pressure. When ready, drain potatoes in a colander over a large pot to hold the water with potatoes out of the water. Cover with a large towel and allow potatoes to cool enough to hold but remain warm.
While potatoes are cooling, in a small bowl, mix mayonnaise, buttermilk, mustard, parsley, dill, 1/2 tsp salt, and 1/2 tsp black pepper. Set aside.
Cut potatoes in half or quarters according to size. Place in a large bowl that has a lid. Pour enough dressing to cover and moisten the potatoes well. Add the chopped celery, chopped radishes, and chopped red onion. Toss and coat well.Add more dressing if necessary. More salt and pepper can be added at serving time. Cover and chill so flavors can incorporate.