Step 1: Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper for easy cleanup.
Step 2: In a large bowl, toss the cubed sweet potatoes with olive oil, smoked paprika, cumin, and salt until evenly coated.
Step 3: Spread the sweet potatoes in a single layer on the baking sheet and roast for 20-25 minutes, or until tender and slightly browned on the edges.
Step 4: While the potatoes roast, heat a small skillet over medium heat. Sauté the red onion and garlic for 3-4 minutes until softened. Add the black beans and lime juice, stirring until warmed through.
Step 5: Prepare the lime crema by whisking together the Greek yogurt and lime zest in a small bowl.
Step 6: Warm the tortillas in a dry skillet or over an open flame for 30 seconds per side.
Step 7: Assemble the tacos by layering the black bean mixture and roasted sweet potatoes onto the warm tortillas. Drizzle with lime crema and top with cilantro, avocado, and pickled onions.