Toss the potatoes in a medium saucepan, cover generously with water and season generously with salt. Bring the pot to a boil and reduce to a simmer until the potatoes are fork tender, about 20 minutes. Drain and reserve.
Coat a large straight-sided saute pan lightly with olive oil. Toss in the bacon and bring the pan to a medium heat. When the bacon is brown and crispy, toss in the onions and cook them until they are very soft and aromatic, 7 to 8 minutes. Add the stock and vinegar. Toss in the potatoes when they are still warm and cook until the liquid has absorbed into the potatoes. Taste and season with salt if needed. Toss in the chives and serve warm or at room temperature.