Preheat oven to 375° F.
Cook quinoa according to package instructions. Drain, transfer to a large bowl, and fluff with a fork.
While quinoa is cooking, peel and chop sweet potatoes into 1 inch pieces. Transfer to a rimmed baking sheet, drizzle with oil, and bake at 375° for 10-15 minutes or until tender. Remove from oven and set aside.
Slice the onion into thin slices. Sauté in a large skillet over medium heat.
To the cooked quinoa, add the roasted sweet potatoes, grape tomatoes, kale, black beans, and sautéed onions.
Combine the dressing ingredients in a small bowl or jar; mix well. Drizzle over the quinoa mixture to taste; toss to combine.