Preheat oven to 425°
Toss sweet potatoes with the olive oil, chili powder, cumin and paprika until evenly coated.
Bake the sweet potatoes for 20 minutes, or until fork tender.
While the sweet potatoes are roasting, add the black beans to a small saucepan over low heat to warm. Flavor with fresh lime juice, salt, pepper and cumin.
If choosing to prepare flavorful beans: While the sweet potatoes roast, heat 2 tablespoons oil in a medium saucepan over medium heat. Add the onions and 1/2 teaspoon salt, and sauté until soft and translucent, 5 to 7 minutes. Add the garlic and jalapeño, and sauté 2 minutes more. Fold in beans.
To assemble the tacos, place the sweet potato mixture into the tortillas of your choice, layer with beans and top with avocado, fresh lime juice, cilantro, tomatoes, jalapenos and/or cotija cheese.
Add additional toppings, as desired.
