Scrub the potatoes and place in a large pot covered with an inch of cold water above them. Set over high heat and bring water it to a boiling point. Add some salt (1 teaspoon to be exact) and boil until tender. This will take around 15-20 min (depends on the size of those so-called small sized potatoes that you chose).
Drain the potatoes and let them cool for a bit.
Once the potatoes are cool enough to handle the next step, peel them using a small knife and cut them into 4-6 slices. Place the potato slices in a large bowl and pour the warm beef broth over the top. Top with the minced onion and white wine vinegar. Season them a little bit with the remaining teaspoon of salt (add more if needed) and freshly ground black pepper, to taste.
Gently and slowly, using a large spoon, stir until all of the potatoes are coated with seasonings.
Cover the bowl with plastic wrap and allow to marinate at room temperature for about 30 min. Stir in the vegetable oil and the parsley and serve immediately, using a slotted spoon if too much liquid remains at the bottom of the bowl.