Scrub the potatoes under running water, quarter them, and drop into a pot of cold salted water. Bring to boil and cook until tender, but still firm, about 8–10 minutes after the water reaches a boil.

Cook the bacon in a small frying pan until crisp. Remove bacon and reserve. In the bacon fat, saute the shallots until tender but not at all browned, 5 minutes or so. Reserve the shallots and fat.

When the potatoes are done, drain them and put them into a mixing bowl. Pour vinegar, olive oil, shallots + bacon fat over the still-hot potatoes. Season with salt and freshly ground black pepper and gently toss. Add the red onion and parsley and toss again. Cool to room temperature, cover, and refrigerate.

Before serving, bring back to room temperature, toss, taste and adjust seasoning, adding additional oil and vinegar if the salad seems dry. Sprinkle the reserved bacon on top.