Preheat oven to 400°F (200°C). On a large baking sheet, toss the diced sweet potatoes with olive oil and taco seasoning until evenly coated. Arrange in a single layer and roast for 20-25 minutes, flipping halfway, until tender and lightly caramelized.

While the potatoes roast, cook the quinoa. In a medium saucepan, bring the quinoa and water (or broth) to a boil. Reduce heat to low, cover, and simmer for 15 minutes or until the liquid is absorbed. Fluff with a fork.

In a small bowl, whisk together the Greek yogurt, chopped cilantro, lime juice, and 1-2 tablespoons of water until you reach a drizzling consistency. Season with a pinch of salt.

Divide the cooked quinoa among four bowls. Top with the roasted sweet potatoes, black beans, and corn. Garnish with avocado slices, diced red onion, and a generous amount of the cilantro-lime drizzle. Serve immediately.