The biggest secret for sweet potato fries is that they don’t crisp like a russet fry. Sweet potatoes have more natural sugar and less starch, but in the air fryer you can get surprisingly close. The starch plus oil combo is what gives you the best exterior, and doing them in a single layer is key. This is the kind of side you keep in rotation because they’re endlessly riff-able: spicy, smoky, sweet, savory, or dipped in mayo, mustard, yogurt sauces — whatever your personal sauce religion is.