Cook potatoes. In a large pot, place potatoes and fill with water until they are just covered. Add a teaspoon of salt and cook over high heat until the water starts to boil. Once boiling, cook until potatoes are fork tender, about 10-15 minutes, then drain.
Preheat oven to 425℉. While the oven is heating, line a baking sheet with aluminum foil. Dump potatoes onto the sheet, and smash each potato to about ¼” to ½” thick. I used the bottom of a glass cup to do it quickly. It’s okay if all the potatoes run together, just try to keep the thickness the same across the entire pan.
Drizzle potatoes with olive oil, then sprinkle with about 2 teaspoons of salt, pepper, and garlic powder. Cook in the oven for 40-50 minutes (flipping the potatoes halfway through) until they start to get a little crispy and browned.
Make the dressing. In a large bowl, mix together sour cream, mayonnaise, dijon mustard, pickle juice, dill, parsley, cayenne pepper, and chives until combined. Set aside until your potatoes are finished.
Add potatoes to the large bowl with the dressing and toss until coated. Serve with additional chives and other seasonings (including fresh herbs if desired) on top.
Notes
To make ahead: Roast the potatoes and make the dressing separately up to a day in advance. Store them in separate airtight containers in the refrigerator, then toss together right before serving so the potatoes stay as crispy as possible.