Boil the potatoes in their jackets until just pierceable.
Pour cold water over them and peel at once.
Cut them into halves or quarters, sprinkle with 1/2 tea spoon salt and add the white wine.
Let stand for 30 minutes.
Mix the oil, vinegar, pepper, 1 teaspoon salt, onion, and parsley, and pour over the potatoes.
If you want to serve the salad warm, you can heat the oil and vinegar, pour them over the potatoes, and toss thoroughly.