Preheat oven to 375° F and line a baking sheet with parchment paper (or spray baking sheet with nonstick cooking spray).
Wash, peel and chop the sweet potato into ½-inch cubes.
Place sweet potatoes on prepared baking sheet. Drizzle with a small amount of olive oil and season with salt, pepper and cumin to taste. Toss with hands until each cube is well-coated. Roast for 40 minutes.
While the sweet potatoes are roasting, cook your quinoa, drain and rinse the black beans and corn, and chop the vegetables.
Place all dressing ingredients in a jar and whisk or shake to combine. Set aside.
Put cooked quinoa, roasted sweet potatoes, corn, black beans, red onion, bell pepper and cilantro in a large bowl. Add dressing and toss to combine.
To serve, spoon the quinoa blend over mixed salad greens, top with sliced avocado, and enjoy!