1. Place potatoes in a large saucepan. Cover with cold water and salt lightly. Bring to a boil over high heat. Reduce heat to medium and simmer for 45 to 50 minutes or until fork tender. Drain and allow to cool slightly.
2. Meanwhile, heat oven to 450 degrees . Place salmon in a baking dish skin-side down and season with 1/8 teaspoon each of the salt and pepper. Bake at 450 degrees for 20 minutes.
3. Peel potatoes, slice into 1/2-inch slices and place in large bowl. Stir in onion. In a small bowl, whisk together mayonnaise, vinegar, dill, remaining 1/2 teaspoon salt, remaining 1/4 teaspoon pepper and the nutmeg. Gently stir into potatoes. Remove skin from salmon and flake with a fork. Fold into the potatoes.
4. Cover and refrigerate for at least 2 hours.