In a large bowl, combine the olive oil, paprika, salt, chili powder, cumin, turmeric, mustard powder and cayenne. Add the sweet potatoes, season with black pepper, and toss evenly to coat.
Transfer the sweet potatoes to the air fryer (save the bowl with the leftover oil and spices) and cook at 400 degrees, shaking the basket halfway through, until golden brown and crisp, about 15 minutes. Return the potato wedges to the reserved bowl and toss again while they are hot out of the fryer.
Meanwhile, in a small bowl, stir together the sour cream and garlic. Season with salt and black pepper and transfer to a serving dish.
Serve the potato wedges hot with the garlic sour cream.