Put potatoes into a medium saucepan, and cover with cold water by about 1 inch. Add 2 teaspoons salt. Bring to a boil. Reduce to a simmer. Cook until tender when pierced with a fork, 15 to 20 minutes. Drain, and set aside until just cool enough to handle; peel if desired. Cut into 1/2-inch-thick pieces.
Meanwhile, stir together shallots, wine, vinegar, and 1 teaspoon salt in a large bowl. Add warm potatoes; toss to coat potatoes. Add parsley, dill, and oil; toss gently to coat potatoes. Season with salt and pepper. Stir in apple. Serve immediately, or refrigerate up to 4 hours; bring to room temperature before serving.