Step 1: Preheat your oven to 425°F (220°C). Line two large baking sheets with parchment paper.
Step 2: Wash and peel the sweet potatoes (if desired). Cut each sweet potato lengthwise into ¼ to ½-inch thick planks, then cut those planks into ¼ to ½-inch thick sticks, aiming for uniform size.
Step 3: Place the cut sweet potato sticks into a large bowl and cover them completely with very hot tap water. Let them soak for at least 30 minutes, or up to an hour. Drain thoroughly.
Step 4: Lay the drained sweet potato sticks out in a single layer on clean kitchen towels or paper towels. Pat them completely dry, pressing firmly to remove as much surface moisture as possible. This step is crucial for crispiness.
Step 5: Return the thoroughly dried sweet potato sticks to the large, dry bowl. Drizzle with avocado oil and toss well to ensure every fry is lightly coated. Then, sprinkle with cornstarch, salt, black pepper, and smoked paprika (if using). Toss again until the fries are evenly coated.
Step 6: Arrange the coated sweet potato fries in a single layer on your prepared baking sheets, making sure not to overcrowd them. Ensure there is plenty of space around each fry for hot air circulation. Use a third baking sheet if necessary.
Step 7: Bake for 15 minutes, then carefully flip each fry using a spatula or tongs. Continue baking for another 10-20 minutes, or until the fries are golden brown and crispy, checking frequently towards the end to prevent burning. Total baking time will vary.
Step 8: Once baked to crispy perfection, remove the baking sheets from the oven. Serve immediately and enjoy your perfectly crispy oven baked sweet potato fries!