Bring a large pot of heavily salted water to a boil (Molly uses about 3 tablespoons salt). Add the potatoes and cook until slightly tender, 6 minutes. Drain and pat dry with a clean towel. Tossing the potatoes back into the drained, still-hot pot briefly can also help some of the excess moisture steam away.
Scatter the potatoes on a baking sheet and season with salt and pepper. Drizzle with the melted butter and toss to coat using tongs or a thin spatula. Roast until the potatoes are dark brown and crispy, 30 to 45 minutes, tossing halfway through. If the potatoes are sticking stubbornly, don’t fuss with them too much—let them keep browning and crisping till they release from the pan.
Meanwhile, in a bowl, whisk together the mayonnaise, vinegar, paprika, sugar and shallots.
You have two choices for serving: You can either serve the salad warm right away, or, if you want to be able to set it out at a party and stay creamy and crunchy for longer, let the potatoes cool before dressing. When ready to serve, toss the warm or cooled potatoes with half of the paprika mayonnaise (save the rest for dipping or another use). Taste and adjust the seasonings as needed. Top with chives and enjoy!