Dill, potatoes, and sour cream go hand in hand. Just ask any Scandinavian and they'll tell you. That said, most Scandinavian-style potato salads tend to be extraordinarily creamy. This version uses only the barest touch of sour cream, instead relying on good technique to pack the potatoes with plenty of flavor and brightness.
Back when I used to work at a hotel restaurant, it was part of my job to prepare all of the food for the overnight cooks to serve on the late-night room service menus. This means lots of pre-formed turkey club sandwiches, a big pot of lobster bisque, a few dozen dumplings, and lots and lots of potato salad. The bad news? I spent a good year and a half of my life making potato salad nearly every single day. The good news? There was no set recipe, which meant that I was allowed to exercise a good degree of poor judgment when preparing it.
"the salad ended up a completely different but equally delicate shade of pastel green"
Most nights, it was good stuff—in fact, it was during this time that I experimented and perfected most of the techniques I employ in my Classic Potato Salad. But I also had my share of failures. The time I decided to blend cilantro into the mayonnaise as I emulsified it in the Robot Coupe and the salad ended up a delicate shade of pastel green. The time I tried substituting wasabi for my normal choice of whole grain mustard and the salad ended up a completely different but equally delicate shade of pastel green (and I'm sure the hotel patron's faces probably matched the salad once they had a taste).
Point is, I've made hundreds of potato salads in my life, and it's not always that I make one so good that it's worth repeating, and even more rare that it's worth writing down and sharing. This version is one of those.
At it's base, it's not dissimilar from my classic potato salad recipe. The key steps are still there: adding the sliced potatoes (creamy fingerlings in this case, though Yukon golds will do) to cold salted water then bringing them to a boil helps them cook evenly and become seasoned throughout. A dash of vinegar ensures that they soften while still retaining their shape (vinegar slows the breakdown of pectin, the organic glue that holds potato cells together).
As soon as the potatoes are tender, I take them out of the pot, drain them well, and transfer them to a rimmed baking sheet, which helps them cool quickly and promotes evaporation of excess liquid. You want to get rid of as much moisture as possible so that your dressing won't get watered down. At the same time, you want your potatoes to be deeply seasoned. Sprinkling them with vinegar while they're still hot allows that vinegar to soak deeply into their core. This is the real trick to getting those potatoes to taste great without having to rely on too much gloppy cream or mayonnaise.
To finish off the salad, I dress the potatoes in a mixture of sour cream, olive oil (the good stuff!), a little more vinegar, some chopped red onion and scallion, and a big ol' pinch of fresh dill.
How good is this potato salad? Let me put it this way: It's the kind of potato salad that it's worth paying a 70% premium plus mandatory $10 tip to have delivered to your door at 3AM.