I've been looking for a way to fry (not bake) sweet potatoes, maybe like the double-fry method for russet and russet-like potatoes, to get a crispy exterior.   Maybe I'm missing something but I'm having difficulty finding something for sweet potatoes (of any kind). I've consulted my cookbook library, and I haven't come across much. I've had mixed experiences with blog recipes, so I trust them less, but maybe this Munchies single-fry-from-frozen sweet potato fries article (which I will try this weekend) has some truth to it?:        Ingredients:         2 pounds large orange-fleshed sweet potatoes    1 teaspoon baking soda    1 cup plus 2 tablespoons cornstarch    Peanut oil, for frying    1 cup clubsoda or water Kosher or fine sea salt      Instructions:         Line a baking sheet with parchment paper and make enough room in the freezer for said baking sheet.   Peel the sweet potatoes, if desired, and cut them lengthwise into 1/4-inch-thick batons (fry shapes). Place them in a bowl with the   baking soda and 2 tablespoons cornstarch, and toss. Arrange the sweet   potatoes on the baking sheet in a single layer, making sure they are   not touching. Freeze them until rock hard, at least 3 hours. If making   fries later, transfer to a gallon-size zip-top freezer bag; they will   keep frozen for up to 2 weeks.   Pour the oil into a large, heavy pot, preferably a Dutch oven, that's fitted with a deep-fry thermometer to a depth of 2 inches. Set   the pot over medium heat and begin gently warming the oil to 375ºF.   In a large bowl, whisk together the remaining 1 cup cornstarch and the club soda. Stack several layers of brown paper on a baking sheet.   When the oil reaches 375ºF, drop a handful of sweet potatoes into the cornstarch mixture and coat evenly. Lift them from the bowl,   letting any excess drip into the bowl, and carefully add them to the   oil. Fry, stirring with a spider so they do not stick to the bottom of   the pot, until deep golden brown and cooked through, about 8 minutes.   Using the spider, transfer the fries to the brown paper to drain.   Immediately season with salt. Repeat with the remaining sweet   potatoes, returning the oil to 375ºF between batches.         I'm looking for validation or refutation of the instructions of that article or, better yet, tried methods from people here that result in crispy sweet potato fries. 
Freezing fries opens up their texture and makes them more fluffy. This is helpful for regular fries or sweet potato fries.  Sweet potatoes have too much sugar and not enough starch to crisp up on their own. The only crispy sweet potato fries I have ever made- or eaten- were coated in starch to provide the crispiness.  While I haven't tried this exact recipe- I haven't used club soda for example- it has all the right steps and looks like it would work. 