Peel and quarter the onions, toss with a small amount of vegetable oil, an.
Bake the sweet potatoes at 350 degrees until easily pierced by a skewer, about 35 to50 minutes. Remove from oven, let cool, then peel and cut into bite-sized chunks. Place in a large bowl with the hominy and red onion.
Dressing: Place roasted peeled chile in blender jar with the citrus juices, oil, and seasonings. Blend until pureed and add to vegetables in bowl. Toss well and let marinate 30 to 60 minutes. Toss with cilantro before serving.