Preheat the oven to 400°F (200°C). Line a large baking sheet with parchment paper. Peel and dice the sweet potatoes into 1/2-inch cubes.

In a large mixing bowl, toss the sweet potato cubes with olive oil (2 tbsp), chili powder (1 tsp), cumin (1 tsp), smoked paprika (1/2 tsp), garlic powder (1/2 tsp), onion powder (1/2 tsp), salt, and pepper until evenly coated.

Spread the seasoned sweet potatoes on the prepared baking sheet in a single layer. Roast for 20-25 minutes, flipping halfway through, until tender and caramelized.

While the potatoes roast, heat 1 tsp olive oil in a skillet over medium heat. Add the ground beef and cook until browned, breaking it up with a spoon. Stir in additional chili powder (1/2 tsp), cumin (1/2 tsp), salt, and pepper; cook for another 2-3 minutes. Set aside.

In a small saucepan or microwave, heat the black beans and corn until warmed through.

Divide the cooked rice into four large serving bowls. Top with roasted sweet potatoes, warmed black beans, corn, and cooked ground beef.

Add chopped cherry tomatoes, diced red onion, cilantro, and avocado to each bowl.

Squeeze fresh lime juice over the bowls. Add optional Greek yogurt or sour cream and salsa. Serve immediately.