Preparation / Directions:
Lace the sweet potatoes and half the mint in a steamer basket and set in a large saucepan over about 1 inch of cold water. Cover the pan and bring the water to a boil over a moderately high heat setting. Steam the sweet potatoes about 15 minutes, or until tender. Add the peas and cook about 5 minutes longer. Drain well and transfer to a large serving bowl. Discard the mint. Add ham and onion, toss to combine.
To prepare the dressing, combine the yogurt, sour cream, vinegar, mustard, salt, and pepper in a small mixing bowl. Finely chop remaining mint leaves and reserve.
Pour the dressing over the sweet potato mixture and add the freshly chopped mint leaves. Toss to combine. Serve the sweet potato salad at room temperature now, or cover and refrigerate until ready to serve.