Preheat your oven to 425°F (220°C). Line a large baking sheet with parchment paper.

In a large bowl, toss the diced sweet potatoes with 1 tablespoon olive oil, chili powder, cumin, smoked paprika, and cayenne (if using). Season with salt and pepper.

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

While the sweet potatoes roast, heat the remaining oil in a skillet over medium heat. Sauté the diced onion for 3-4 minutes until softened.

Add minced garlic to the skillet and cook for another minute until fragrant.

Stir in the black beans and cook until heated through, about 3-4 minutes.

Warm your tortillas either in the microwave wrapped in a damp paper towel, or directly over a gas flame for added char.

Assemble the tacos by filling each tortilla with the roasted sweet potatoes and black bean mixture. Top with your chosen garnishes.