Add the potatoes, vinegar and 1 tablespoon of salt to a large pot and add water to cover by 1 inch. Bring to a boil, reduce to medium-high heat and simmer until fork tender, about 25-30 minutes.
Preheat the oven to 450 degrees. F and line a baking sheet with parchment.
Drain the potatoes and return to the pot. Add 3 tablespoons olive oil, 1 tablespoon of vinegar, 1 teaspoon salt, and ½ teaspoon black pepper; toss together. It's okay if the potatoes fall apart.
Transfer the potatoes to the prepared baking sheet and spread into a single layer. Bake for 25-30 minutes, or until crispy. Once done, toss the potatoes with the last 2 tablespoons of vinegar.
Garnish with chives and flakey sea salt, if using. Serve with sour cream.