To make the dressing, combine all dressing ingredients in a blender or food processor and process until well blended.
Preheat oven to 400 degrees.
Toss sweet potatoes with the oil, chipotle chile powder, and salt until well coated. Spread potatoes in an even layer on a baking sheet and roast at 400 degrees until tender and beginning to brown on the edges, about 30 minutes.
Place chopped romaine in a large bowl. Give your dressing a good stir, then pour over lettuce and toss to coat evenly. Divide lettuce evenly between plates. Top each with equal amounts of roasted sweet potatoes, black beans, chopped avocado, and crumbled goat cheese. Garnish with cilantro sprigs, pepitas, and thinly sliced red onion.