2 pounds fresh waxy potatoes, such as Yukon Gold or your market recommendation 1 medium fresh sweet onion, such as Walla Walla sweet or Vidalia, chopped 1 bunch green onions or new shallots, white parts chopped handful fresh cilantro, basil or Italian parsley, chopped 1 cup mayonnaise 1/2 cup buttermilk 2 tbsp cider vinegar, or, your favorite vinegar 1 or more tsp chopped fresh herbs, such as chives, thyme, oregano and dill 1 tsp salt fresh ground black pepper and cayenne pepper to taste Scrub potatoes and cook in salted boiling water until just tender when pierced with a paring knife; remove from heat and drain Mix mayonnaise, buttermilk, vinegar, herbs and spices in a large bowl When potatoes are cool enough to handle, dice into 1/2 to 1 inch cubes Add potatoes, onions and green onions to dressing in bowl and mix to coat Taste; adjust seasonings Refrigerate until ready to serve; make ahead if possible to give flavors time to meld