In a large pot fitted with a steamer basket, steam the sweet potatoes in batches until just tender, 12 to 15 minutes per batch. Transfer them to a large bowl and let cool to room temperature.
Meanwhile, in a small bowl, make the Orange-Maple Dressing by whisking the olive oil, maple syrup, orange juice, vinegar, ginger, nutmeg and salt.
Add the green onions, parsley, pecans and raisins to the cooled sweet potatoes. Pour the Orange-Maple Dressing over the potato mixture and toss gently to combine. Season to taste with salt and pepper. This salad can be made several hours ahead of time; cover and refrigerate until ready to serve.