1 Preheat oven to 200°C and line two large baking trays with baking paper. Cut each potato lengthways into wedges. Arrange on trays, sprinkle lightly with chilli powder and spray with olive oil. Bake the potato wedges for 30 minutes.
2 Meanwhile, heat a chargrill pan over medium-high heat. Cook corn for 12–15 minutes, turning occasionally, until tender and charred. Cool, then cut kernels from cobs. Combine red onion and lime juice in a bowl; set aside.
3 Arrange the cooked sweet potato on a large baking tray. Combine the beans and taco sauce in a bowl and spoon over the sweet potato. Sprinkle with cheese. Bake for 10 minutes.
4 Top with corn kernels, tomatoes, onion, avocado and coriander. Dollop with sour cream, or serve on the side. Serve immediately, with lime wedges to squeeze.