Preheat your oven to 200C (400F) and line a large baking sheet with parchment paper.
In a large bowl, toss the cubed sweet potatoes with 2 tablespoons of olive oil, cumin, smoked paprika, chili powder, salt, and pepper until evenly coated.
Spread the sweet potatoes in a single layer on the baking sheet. Roast for 25 minutes, or until tender and browned at the edges.
While the potatoes roast, heat 1 teaspoon of olive oil in a skillet over medium heat. Add the minced garlic and sauté for 1 minute until fragrant.
Add the rinsed black beans, cumin, and lime juice. Cook for 3-5 minutes until heated through.
Warm the tortillas in a dry skillet or over an open flame for a few seconds.
Assemble the tacos by layering the warm black beans, roasted sweet potatoes, crumbled feta, red onions, and fresh cilantro. Serve warm with lime wedges!