Preheat the oven to 220°C (425°F) and line two large, rimmed baking sheets with parchment paper.
Peel and cut the sweet potatoes into fry-shaped pieces about ½ cm ( ¼ inch) wide and thick. Aim for similar sizes to ensure even cooking. Divide the uncooked fries evenly between the two baking sheets.
Sprinkle each pan of fries with 1½ teaspoons cornstarch and ½ teaspoon smoked paprika. Toss until evenly coated. Drizzle 1 tablespoon olive oil over each pan and toss again until all fries are coated, with no powdery spots remaining.
Arrange the fries in a single layer, ensuring they’re not overcrowded. Bake for 15 minutes, then flip the fries and rearrange them in even layers. Move any particularly browned fries toward the middle of the pan to prevent burning. Swap the baking sheets’ positions (top pan to the lower rack and vice versa).
Bake for another 10-15 minutes, or until the fries are crispy. Keep a close eye on them as they can quickly go from crisp to burnt.
While the fries bake, heat the chili, grate the cheese, and chop the tomatoes, onion, and avocado (or make guacamole).
Either create one large sharing tray or serve individual portions for everyone to build their own. Start with adding the cheese, then chili, a little more cheese, and finish with your chosen toppings. Serve immediately.