This is my favorite way of making potato salad. Sometimes people add hard-cooked eggs, or pickles, or bacon, and those things are all good, but I prefer just the basics.
About three quarts of small Russet potatoes (or another kind with waxy skin- even though I love Yukons, they are not good for this), cut into pieces
2 shallots, chopped fine
About 3/4 C dill, chopped
1/2 C green onions, sliced fine
1 C white vinegar
1 C sour cream (light works fine)
1 C mayonnaise
Boil or steam the potatoes until they are tender enough to spear with a fork, but still firm enough to hold their shape. Drain and toss with the vinegar, dill, shallots, and some salt and pepper. Let cool.
When cool, mix the sour cream and mayonnaise with the potatoes. Top with the green onions and serve.