Guaranteed Crispy Sweet Potato Fries & Sriracha Mayo Dip

There are two ways to get guaranteed crispy sweet potato fries.  In your oven (yes!) or in a deep fryer. But even deep frying plain sweet potato fries won’t get them crispy. You need a tiny bit of the secret ingredient – cornstarch.

Skip right to the printable recipe.


Right here, right now I am going to teach you how to make crispy sweet potato fries. Even though they’re not a real french fry. They are french fry substitutes to be eaten when a real french fry can’t be found. 

Yes, I know.  But you loveeeeeeeee sweet potato french fries.  You like them wayyyyyyyyyy better than regular french fries.  That’s because you’re an amateur.   I on the other hand, am a french fry professional.

I have been making, eating and gorging myself on theses sticks of potato deliciousness for as long as I can remember.  In high school I ate so many of them at lunch that at the end of the year I threw up a ball of grease.  So … clearly … a professional here whose advice should be followed. 

But … if you’re on some sort of stupid meal plan, or you’re all out of regular potatoes, or you just feel like having something a little different than regular french fries, why wouldn’t you cook up some Sweet Potato French Fries?

Because they’re soggy messes.  That’s why. They’ll get brown but they don’t get crispy.

I’ve oven baked them, par boiled them and deep fried them and they don’t get crispy.  They get brown, but not crisp.

Finally, I’ve figured out how to make crispy sweet potato fries and the best part is you can do them in the deep fryer or the oven!  Either way, you’ll end up with crispy fries.  Guaranteed.

But like with most things, you’re more guaranteed if you do them in the deep fryer.

Here’s what you need to do to create this perfect sweet and spicy lunch or side dish.


Gather your sweet potatoes.


Get some corn starch.

Also get some olive oil. Just the cheap stuff.  Not the good stuff like my favourite Lorenzo No.5. Seriously best tasting olive oil ever.

Peel your sweet potatoes.  I have used the same brand of vegetable peeler for 15 years now.  It’s the cheapest, most basic vegetable peeler around and it’s pretty much every cook’s favourite.  It’s the Great Lash mascara of the vegetable peeling world.

Cut your sweet potatoes until they’re a medium thickness.  Not hugely thick cut and not shoestring.

Let potatoes soak in water for an hour – half the day.  (not mandatory, but recommended)

Preheat oven to 425°

Throw a Tablespoon or two of cornstarch into a plastic bag.

(update:  I’m reducing this to a definite 1 Tablespoon of cornstarch because people were reading this as 1 to 2 to 173 Tablespoons of cornstarch.  So it’s a hard 1 Tablespoon now.  Got it?)

Dump a handful of sweet potatoes into the bag with the cornstarch.  You don’t need to dry them with paper towels or anything.  Just drain the water and then give each handful you drop in the cornstarch a good shake.  Twist the top of the bag so it forms a balloon with some air inside and shake the fries around until they’re lightly coated with the cornstarch.  This is important.  Too much water and too much cornstarch and you’ll end up with a goopy mess.  Plus your fries will taste like cornstarch.

Put them on a non stick cookie sheet. The darker the cookie sheet the better – all the better to brown with.

Drizzle 2 Tbsps. of olive oil over the sweet potatoes. This is if you want to be healthy.

Any vegetable oil will work.  I’ve used sunflower, avocado, vegetable etc. etc. 

Saturated and Unsaturated Fats

Saturated Fats for frying

  • Lard
  • Tallow


Monounsaturated & Polyunsaturated Fats for frying

  • Olive Oil
  • Canola Oil
  • Peanut Oil
  • Sunflower Oil

You can use as much oil as you want.

(Update: The more oil you use the easier time you’ll have of getting the fries crispy but the less healthy they will be.)

I usually go the totally unhealthy route to make sure the fries are crispy. Just drizzle the oil across them and then mix them up with your hands to coat well.

Spread the whole mess out evenly on your baking sheet.

Arrange them so they have space between each fry.  The less of them on the pan the better they’ll cook.  Too many shoved together and they’ll never get crispy.  They’ll just steam.  So do NOT overcrowd the pan.  Pop the pan into your preheated oven and cook for 15 minutes.

Meanwhile you can make the dipping sauce.  Mix together 1/2 cup of mayonnaise with 1 teaspoon of Sriracha sauce and 1/4 teaspoon of Cayenne Pepper.

You can adjust the proportions to taste.  Mix it up and taste it then adjust as you like.

Check them after 15 minutes, flip them over (you might have to use a spatula depending on how “non stick” your pan is) and return to the oven if necessary for another 5 minutes.  The timing really depends on the size of your fry, the heat of your oven and how well your pan conducts heat.

(update:  You can see the pan I’m using here is very dark, this very dark, old, used pan cooks things faster and crispier. So if you have an old pan like this use it.  If you have a shiny, new baking sheet your fries will take much longer to cook, will have a greater tendency to stick and won’t get as crispy)


Yes. Guaranteed. Crispy. Sweet Potato Fries. There's one secret ingredient (corn starch, so not so secret) and a few tips and techniques that you have to follow. But if you do, it'll work and no more soggy sweet potato fries.

Maxwell Williams French Fry and dipping cup!!

If you prefer your food deep fried, (and who doesn’t) throw them in the deep fryer at the highest setting for a few minutes instead of sticking them in the oven. You STILL need to coat them in cornstarch.  Even in a deep fryer, sweet potatoes fries won’t want to get crispy unless they have a coating of cornstarch.

This is how I do them when I’m in a rush.  They’re always crispier than those from the oven, but far less healthy.

See? French fry professional.

Guaranteed Crispy Sweet Potato Fries & Sriracha Mayo Dip

4.58 from 7 votes
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Author: The Art of Doing Stuff


  • 2 large sweet potatoes
  • 1 Tablespoon of cornstarch
  • *Dipping Sauce*
  • 1/2 cup mayonnaise
  • 1/4 tsp. cayenne pepper
  • 1 tsp or more Sriracha sauce


  • Preheat oven to 425 or deep fryer to highest setting
  • Peel sweet potatoes, slice into medium thick slices (closer to thin than thick).
  • Soak potatoes at least 4 hours in water.
  • Drain water from sweet potatoes and shake dry with your hands.
  • Put 1 Tablespoon of cornstarch into food safe plastic bag.
  • Dump sweet potato fries into bag, blow some air into it, and shake bag until fries are coated.
  • Place fries on cookie sheet, drizzle with a couple Tablespoons of olive oil.
  • Toss fries until evenly coated with oil.
  • Arrange on cookie sheet(s) with lots of space in between fries to prevent steaming.
  • Cook in hot oven for 15 minutes then check.
  • The fries will release from the pan when they're ready to flip the same way a steak would.
  • Flip fries, and continue to cook for another 5-10 minutes.
  • (cooking time depends greatly on the quality of your baking sheet so keep an eye on them)
  • Dipping Sauce: Mix together mayo, pepper and Sriracha sauce. Adjust to your taste.


  • Do NOT use too much cornstarch. It will lead to heartache and raw, powdery tasting fries.
  • A dark, metal baking sheet will give the best results.
  • Sweet Potato Fries will get dark fast because of their high sugar content. Don't forget to flip and turn them.


  • Do NOT use too much cornstarch. It will lead to heartache and raw, powdery tasting fries.
  • A dark, metal baking sheet will give the best results.
  • Sweet Potato Fries will get dark fast because of their high sugar content. Don’t forget to flip and turn them.

Please note :  This recipe does have a bit of a learning curve.  It may take a few attempts to get your proportions of corn starch and oil correct.  It took me several years to figure out how to do this, but with these instructions it shouldn’t take you more than a couple of tries.  

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Guaranteed Crispy Sweet Potato Fries &  Sriracha Mayo Dip


  1. mary sober says:

    These looked so delicious that I admittedly was too impatient to soak for any amount of time as I had to leave shortly…. They still turned out amazing!!!! I love sweet potatoes but every time I have previously made fries they were dry or squishy. I did use a little more cornstarch than recommended , but they are crispy and yum!!!!!! Thanks

  2. Gabi says:

    The title of this recipe desperately needs to be changed; you cannot claim to “guarantee” crispy sweet potato fries and then add a disclaimer at the end of the recipe to warn people that it may take many attempts to achieve the results this recipe originally “guaranteed.” If the recipe and instructions are so specific and approaches need to be modified several times in order to be successful, the results you’ve achieved are clearly highly unattainable for most people reading through this recipe. Attacks on individuals who find this method unsuccessful and comment on it also seem unnecessary. I followed this recipe perfectly and I think my fries turned out soggier than they ever have before. Disappointing.

    • Karen says:

      Hi Gabi! Very brave of you to comment. Tt is not a magic recipe. It is a recipe that needs to be followed. When it’s followed, the fries are crispy. The results I’ve achieved are not clearly highly unattainable. ~ karen!

  3. Kathy Salkeld Bonilla says:

    Mine were perfect, made in a gas oven here in Vilcabamba, Ecuador, using an OLD pan! Thanks for the GREAT recipe! I made a garlicky, hot spicy dip with greek yogurt and homemade mayo, yum! I also make yucca fries which I love with garlic mayo…

  4. Susan says:

    I just found your blog yesterday. Found this recipe and laughed at all the comments and your replies! I laughed out loud at the “shove it” to the anonymous poster. Made the sweet potatoes tonight for dinner and they were pretty crispy. I know I could have gotten them crispier if I left them in a bit longer but I got impatient. I will make them again for sure.

    And I totally remember you from your t.v. days! I’m glad I stumbled upon your website. Can’t wait to look around some more!

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  6. Ginger says:

    Even though this is a relatively older post, I wanted to put my 2 cents in! I always read comments before I try recipes and hope that this will help someone. I tried this recipe last night and it was a success!! I cut my potatoes pretty close to what you have pictured and rinsed them twice before soaking for about 4 hours. I then drained the water and left the potatoes in the bowl until I was ready to fry them. I put some potatoes in a zip bag and sprinkled some cornstarch in there and shook it around. Then I fried my potatoes in vegetable oil in my fryer set at 400 degrees for 3 1/2 minutes per batch. They were perfect! Even my sweet potato-hating hubby said they were great!!

    • Karen says:

      So … you followed the instructions. ;) That really is the issue most people have even though they don’t realize it. They shorten or just plain skip some of the steps. Glad they worked for you and I hope you made the sauce! ~ karen

  7. Shauna says:

    Darn, I’ve tried twice to make these, because they look so amazing. Both times they stick like crazy to the pan and they don’t get crispy. So sad. I wonder if they don’t work at altitude, I’m at 7500ft. I’m going to try coconut oil next time, and maybe cooking them on a rack instead of on a plain flat pan. :-(

    • Karen says:

      Hi Shauna! If they’re sticking like crazy it sounds like your pan isn’t cooperating. I’m guessing it’s a fairly light coloured pan? Try using more oil. I would continue to use olive oil if you can. And don’t try to turn them until they’re good and brown. Kind of like a steak, that will release from a grill once it’s been browned, so will the fries. The other thing you can do is go to a secondhand store and get an old, used cookie sheet. One that’s nice and dark. They are great for browning things and having great non stick properties after all the years of baking on them. :) ~ karen!

      • Shauna says:

        It’s a dark old pan. Thank you, Karen. I’ll try more oil and holding off on turning them.

  8. rida ali says:

    can i make these in a toaster oven?

  9. judy says:

    Once again I have to say you have amazing advice and ideas. You are not only a french fry professional, you are a genius.

  10. Jennifer Harris says:

    After many years of trying to make CRISPY sweet potatoe fries in the oven, I finally ran across your recipe. Hoorah! They came out SO CRISPY and yummy. I did add a little sprinkle of dried rosemary, seasoning salt, garlic powder, lemon pepper and paprika on them right before I put them in the oven. They were delicious!!! I used some yogurt, a little mayo and Grey Poupon to dip them in> Any spices the cook fancies can be used, of course, but what a treat not to have soggy and some burned. Thank you, keep up the good work!


  11. Christine says:

    I will try this recipe but felt the need to address the “stupid meal plan” comment. I have spent almost three months in hospital and have developed IBS after bowel surgery. Sweet potato is one of the few vegetables that doesn’t trigger gut/bowel issues for me. Stupid meal plan or making the best of things? There are many people out there who rely on different foods to sustain themselves in a healthy way – so please reflect on this before labelling it as a stupid meal plan

  12. Khaili says:

    Baked these last night in the oven. So amazing! Totally crunchy! Thank you!!!

  13. uraina says:

    Karen, cornstarch was the best secret I discovered a few years back for SP fries. I season my cornstarch though with Kosher salt, cayenne pepper, chili powder, and garlic powder. When they’re done I give them a sprinkle of Old Bay seasoning, A-MAZ-ING! I have never soaked them in water though, I will try that next time to see if I can tell the difference. Also, that dipping sauce sounds amazing, will have to try that as well.

  14. Kristal says:

    Sweet potato fries are one of my all time favorites, this recipe looks good!

  15. Naomi says:

    This is the first time I made them. I used our home grown sweet potatoes! Not to bad my hubby like them too! I think I will use less cornstarch next time.
    Thanks for all the time you put into making the recipe work!

  16. ladyrose says:

    Just made these for dinner. We did the deep fry method. Worked perfectly!! We are very happy little sweet potato fry consumers now. Btw, we always serve ours w/ a little shot glass of maple syrup for dipping. Yummy!!!

    • Karen says:

      Glad they worked out well for you ladyrose! I always laugh when people use something sweet to dip their sweet potatoes in. I make my sauce as hot as possible to cut the sweet. Something most of my family members are appalled by. ~ karen!

  17. Elin says:

    Made these tonight for the first time and they turned out perfect!!!! Fantastic recipe! Thanks for sharing!

  18. Keli says:

    A-MAZ-ING. I’m a few years behind the crowd here, but thank you for the great recipe. My pan wasn’t non-stick so I coated it with oil – the fries still stuck a bit (so I jumped on Amazon and ordered a non-stick cookie sheet because we MUST have these again!). They were delicious. I assume they were meant to be salted at the end (because what’s a fry without salt?).

    I’m not much of a spice girl, so I cut down on the Siracha. Used 2/3 greek yogurt and 1/3 mayo – added a few shakes of garlic salt to make up for it. Delicious.

    Served with a huge green salad for a delicious veggie meal. Will make these again and again.

    • Karen says:

      Excellent Keli! Also remember the longer you use a non stick cookie sheet and the darker it gets (from cooking on it in the oven) the better it will be. So don’t be disappointed if it isn’t great at first. That’s just the way they are. ~ karen!

  19. mila furman says:

    Karen I am drawn to your blog not only because of the gorgeous pictures but because I have a culinary background as well as I prefer to do most things the scientific route! So I bet this will do juuuuust fine :)

  20. mila furman says:

    Karen so glad to have found your blog!!! I never would have thought to do this!! Love it! Pinned and definitely trying it out!

    • Karen says:

      Hi Mila. Welcome to The Art of Doing Stuff! As you can see there’s varied results with this recipe, lol. But if you follow my instructions you’ll do fine. And don’t forget to make the dip! ~ karen!

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