Preheat the oven to 425°F / 220°C. Line a baking sheet with parchment paper.
Add the cubed sweet potatoes to the prepared pan. Drizzle with olive oil and season with cumin, smoked paprika, salt, and black pepper. Toss to coat and spread into a single layer.
Roast for 25 to 30 minutes, stirring halfway through, until the sweet potatoes are tender and browned around the edges.
While the sweet potatoes roast, heat a large skillet over medium-high heat. Add the ground beef and cook for 6 to 8 minutes, breaking it apart with a wooden spoon, until browned and fully cooked.
Drain excess grease if needed. Stir in taco seasoning and water or broth. Reduce the heat to medium-low and cook for 2 to 3 minutes, until the beef is evenly coated and most liquid has evaporated.
Warm the black beans and corn in a small saucepan, microwave, or skillet, if desired.
In a small bowl, mix Greek yogurt, lime juice, cilantro, garlic powder, salt, and 1 tablespoon water. Add another tablespoon of water if needed to create a drizzleable sauce.
Divide the roasted sweet potatoes among four bowls. Add taco-seasoned ground beef, black beans, and corn.
Top each bowl with avocado, red onion, cilantro, and Greek yogurt lime sauce. Serve with lime wedges.