Preheat the oven to 200C/180C fan/Gas 6. Toss the sweet potato cubes and onion wedges with the oil, smoked paprika, cumin, chilli powder and a good pinch of salt.
Spread on a baking tray and roast for 20-25 minutes until the sweet potato is tender and slightly crispy at the edges.
Warm the black beans in a small pan or microwave. Season with salt and pepper.
Warm the tortillas in a dry pan for 30 seconds each side.
Fill the tortillas with roasted sweet potato, black beans, diced tomato and grated cheese. Add a dollop of yoghurt and a drizzle of hot sauce.