I’m so excited and relieved to finally have a method that gives delicious results. If you’re looking for a recipe for homemade, super crispy sweet potato fries, look no further. This is not hard & stale-crispy, not soggy & slightly crispy, and definitely not charred-crispy. I’m talking about about that pleasant, light crispiness that lasts long enough to enjoy your meal.
This requires deep frying though. No exceptions.
It’s been a long journey
I’ve tried so many recipes and ended up having to narrow it down all the details myself: baking vs. frying, bake & fry temperatures, fry thickness, amounts of cornstarch, drying, dark vs. light baking sheets, and more combinations of these variables than I care to count. I took notes on the process as I changed these details one at a time.
Kudos to all the home cooks out there who can achieve crispy baked sweet potato fries. I began with baking and got piss-poor results. The fries were too limp, dry, burned, or soggy. I must admit one method (possibly important?) I couldn’t test was baking in a convection oven. There’s probably some obvious mistake I made or something, but baking did not work for me and for that fight, I threw in the towel.
All this testing finally led to a great recipe I’m happy to share with you. As with most simple things in life (and recipes), the little details are important.
1. Clean the sweet potatoes
You don’t want to eat dirt. Scrub these well under running water with a vegetable scrubber or rough sponge.
2. Cut into matchsticks
You can peel off the nutrition-rich skins if you want, but it does not matter for the crispness in this recipe. My cheap vegetable peeler almost broke during these sweet potato making sessions. When I replace it, I’d want this one.
Thickness of the fries is important because it affects later steps.
If you want sweet potato fries with more ‘creamy’ center, go for 1/2″ fries. If you want more fried-to-potato ratio, then go with 1/4″ fries.
Try to keep the cut as uniform as you can. Using a mandolin for this is near impossible unless you’re the Hulk. If you want perfectly uniform fries, my choice would be this professional cutter with the 1/2″ cutting grid.
Or tough it out with your favorite knife and have the fries all slightly different. Like mine:
3. Rinse to remove excess starch
You do not need to soak them.
Run them under water and swish it around. Dump the water, and repeat one more time. Soaking even for an our after this 2nd rinse did not release any extra starch.
4. Dry the fries
We want to dry these up a bit so they aren’t dripping. I like to use this small salad spinner because it works very well. Otherwise just shake ‘em out and pat dry with paper towels or some kitchen towels.
I do this for 1/2″ fries only. 1/4″ fries don’t really need par-cooking.
Par-cooking ensures its cooked all the way to the center. Without it, the heat of the oil will burn the outside before the center cooks or you will have raw centers. Par-cooking lets us focus on doneness now and crisping later.
I like to boil them because it’s much faster and more importantly the sweet potatoes retain their rich color.
Baking (works, but won’t use again)
It works, and you can get creamy 1/2″ fries. This method takes more than twice as long and you lose the great orange color. The only benefit I can see from this is that it’s more hands-off and you’re less likely to overcook them.
I tried par-cooking with a cooling rack on a cookie sheet at 325°F for about 30-45 minutes. When cooked through they are slightly leathery on the surface. This texture remains shortly after frying, but actually went back to normal with good creamy centers after 5-10 minutes. Avoid this trouble and just boil them.
6. Fry method & secret to crispiness
Well it’s a combo of the cornstarch batter and cooking method. A lot of recipes tell you cornstarch was the game changer for them too, but most sprinkled it straight onto the fries. I couldn’t get that to work for me.
So use this cornstarch batter. For a small-medium sweet potato, I use a light batter of 4 parts cornstarch to 3 or 4 parts water. If its kind of milky looking, you’re good to go. This stuff sludges up fast (30-60 seconds?), so mix it up (add water if necessary) right before you put a handful of sweet potatoes in it every time before you dip.
If it’s sludgy, your fries will come out caked in hard, white starch.
Type of oil
We want a neutral tasting oil with a high enough smoke point, so peanut, canola (rapeseed), or vegetable oil are some that work.
Managing oil temperature
Use a dense pot with sides high enough to prevent excess splatter. We want to maintain a temperature of 325°F-350°F as closely as we can throughout the entire fry session. The denser your pot, and the more oil you use, the more stable you can expect the temperature to be during cooking. I’m getting by with a thin pot and oil almost half way up the sides, so I have to fry less per batch to maintain the temperature.
You need a thermometer. Oil that’s too hot or cold will yield poor results. You need to know when to start adding fries to the pot. And when you add a batch, the oil temperature will drop. Knowing how to adjust to temperature changes is very difficult without a thermometer.
A deep fry thermometer is designed for this task. However, I like to use my all-in-one probe thermometer for this (you can see the probe hanging into the fry pot above). I let the timer run to know the duration of each frying batch. You can set specific alarm times at 2 minutes if you want.
Let’s quickly recap the process
Wash, cut, rinse & dry the sweet potatoes.
Mix cornstarch batter. Dip and fry. Then dip and fry again.
See recipe below for full step by step instructions.
Possible future improvements
Batter: adding herbs or seasonings into this step. Different starches for the batter for even better results? Arrowroot, rice flour, or some blend. Maybe one that doesn’t sludge up so quickly.
Dipping sauce: mayo, chipotle aioli, super garlicky aioli, homemade.
Cooking: faster way to evenly dip and fry more fries at once.
- 2 medium sized sweet potatoes
- cornstarch for batter
- oil for frying (peanut, vegetable, or canola)
- seasonings (paprika, pepper, salt)
- Wash, peel (optional), and cut into ½” or ¼” matchstick shape fries. ½” (preferred) will require par-cooking.
- Rinse under running water, drain and repeat once more. Dry in salad spinner or with towels.
- To par-cook: boil in water until tender, and just cooked all the way through, not mushy and breaking in our hands. About 8-15 minutes.
- Make some batter. About 4 parts cornstarch to 3 or 4 parts water until milky, but not too watery.
- Dip fries (I do about 5 so they don’t sit there as the cornstarch gunks up). Shake off excess.
- Quickly drop into the fryer 1 at a time so they don’t stick. About 1-2 minutes at 325°F-350°F. We don’t want it to brown too much yet.
- Remove from oil, rest on paper towels to remove oil and cool off.
- Repeat to finish all the fries, making sure you mix up the batter before each small batch (For me, each set of 5 fries). You might have to add some water if the batter is sludgy.
- So after the first batch, they’re pretty good now, but you have to eat them quickly or they lose the crunch. I have discovered that a 2nd dip & fry makes the crunch better and last much longer.
- Dip + fry a 2nd time, following the same steps. Except this time you can leave them in the oil until the fries brown enough to your liking. It still should be around 1-2 minutes. Season each batch while hot. I like salt, paprika, and finely (freshly) ground pepper.