The Trick For Crispy Sweet Potato Fries Requires No Extra Ingredients
If you've already mastered how to make regular French fries crispy, you might assume you'd have no issue achieving the same results when making sweet potato fries. Unfortunately, that isn't necessarily the case because sweet potato fries are a lot more difficult to crisp up due to the fact that they naturally contain more moisture and sugar compared to other varieties. For sweet potato fries that are actually crispy, many recipes call for coating them in a layer of cornstarch or flour. But while this technique is effective, you don't actually need the extra ingredient.
Whether you're baking them or frying them, the easiest way to ensure your sweet potato fries turn out crispy is to simply space them out so none of them are touching each other. It may be tempting to overcrowd your baking pan or fryer so you can cook everything in one batch, but this will inevitably lead to soggy fries. Instead, if you are cooking a lot of fries at once, use more than one pan.
Why overcrowding leads to soggy sweet potato fries
Overcrowding prevents crisp for two different reasons. When baking, it's because of trapped steam. This steam can come from the natural moisture of the potatoes, but it can also come from failing to dry them after soaking them in cold water. With nowhere else to go, the moisture will turn to steam when baking, and the fries will become soft. It's for the same reason that the side of the fry touching the pan will usually be a lot less crispy. If you want to avoid this, in addition to spacing the fries out, make sure to either flip them halfway through baking or bake them on a wire rack.
When it comes to sweet potato fries that are fried in oil, overcrowding leads to soggy fries for another reason. It has less to do with the moisture, but rather the fact that adding more food to the oil causes its temperature to drop. When the oil isn't hot enough, the sweet potatoes absorb more and take longer to cook, ultimately preventing them from crisping up.
Making sweet potato fries even crispier
Since a major reason sweet potato fries don't crisp up well is their higher moisture content, the more moisture you get rid of, the crispier they'll be. One way to reduce the moisture is to fry them twice, first at a lower temperature, then once again at a higher one. The first round of frying will rid the potato of moisture without it burning, while the second round will finish off the rest of the cooking.
If you're using the oven instead, you can draw out moisture a different way, by first blanching and freezing them. The freezer has a drying effect on fries, and this is especially useful when making sweet potato fries.
These techniques by themselves are effective with regular fries, but when making sweet potato fries, you do want to make sure you're still spacing them out as they cook, as this will fully ensure the texture will be crispy every time.