Syn Free Crispy Sweet Potato Fries

Growing up I was never a fan of sweet potatoes, they reminded me of the bland watery vegetable mash that was served with school roast dinners! However over the last couple of years, I’ve realised that sweet potatoes can be a beautiful thing!

For some reason it has taken me a really long time to perfect sweet potato fries, because every time I cooked them in the past they were just soggy and frankly pretty awful! At this point I’ve got to give a very big shout out to Eb over at Easy Peasy Foodie (fantastic blog!) for giving me the confidence to try and make them again with her excellent advice, as I had all but given up.  As I think anyone on Slimming World will know, sweet potatoes are a free food, and they can make a really lovely change from regular potatoes (which I eat a lot of!) as a side for everything from steak to chicken.

I decided to give them a go again, as I was recently sent some of the new Heinz Seriously Good Mayonnaise to try out, and I couldn’t get that delicious combo of sweet potato fries and mayo out of my head. I decided that it was only fitting to try these out again, and the wonderful thing is that because the sweet potato fries themselves are completely syn free and full of flavour, you can add a dollop (or more) of Heinz Seriously Good Mayonnaise without any guilt whatsoever! One level tablespoon of Heinz mayo is 5 syns, so it is a bit of a treat but it’s a very very worthwhile one I promise. 

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I have to be honest with you, I was pretty sure mayonnaise couldn’t really be changed that much…it’s mayonnaise after all, we all know what it tastes like! Well, as it turns out, when Heinz decide to call something ‘Seriously Good Mayonnaise’ they’ve not done it without good reason! This new mayonnaise is actually delicious, so I can highly recommend it. I’m going to be testing it out on the family soon…so hang tight for the taste test, it’s going to be a Heinz VS Hellman’s battle for mayonnaise glory!

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What I realised when perfecting these sweet potato chips was that in the past I had been treating them like regular white potatoes, expecting them to cook in the same way and within the same time frame. What I’ve since realised is sweet potatoes seem to have a lot more moisture in them, so they go soggy before they go crispy, and it’s just a case of sticking it out and making sure you don’t let them get burnt in the process! If you’re like me and always find that your sweet potato fries go soggy, then hopefully my process below will work for you too!

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Serves 2

Syn Free Sweet Potato Fries

Crispy, sweet, and perfect for sharing!

10Prep Time

50Cook Time

60Total Time

Save RecipeSave Recipe


  • 2 Large Sweet Potatoes (skin on)
  • Fry Light
  • 2tsp Paprika
  • 1tsp Cumin
  • 1tsp Mild Chilli Powder
  • 1/2tsp Salt
  • Black Pepper (to taste)
  • Heinz Seriously Good Mayonnaise (to garnish)
  • Spring Onion (to garnish)
  • Parsley (to garnish)


  1. Preheat your oven to 200 degrees.
  2. Slice your sweet potatoes into discs from bottom to top, so that they are the longest they can be (not from side to side unless you want small chips).
  3. Slice each disc into three or four chips, and place in a bowl.
  4. Spray the chips in the bowl with some Fry Light, I used about 6 sprays, and then add the dry ingredients.
  5. With your hands mix everything around until the chips are coated as evenly as possible.
  6. Tip them out onto a large baking tray, and then spread them evenly so they're not touching each other. If you need to use two baking trays then use two as this is where they differ from regular potatoes for me because with regular potatoes I'll just chuck them in and know they'll cook!
  7. Place in your hot oven, and leave to cook for about 25 minutes or until they move on the tray without needing to use a spatula to move them.
  8. Using a spatula, turn the chips over onto the non crispy side, which will still seem quite soggy, and place back in the oven until they're done to your desired crispiness. For me this was about 25 more minutes.
  9. Split into two serving dishes and serve with mayonnaise, chopped spring onion and a few sprigs of parsley to garnish.


The sweet potato chips are syn free on Slimming World. Add syns for the mayonnaise.


Calories: 176 cal
Carbohydrates: 33 g
Fat: 4 g
Sodium: 725 g
Cholesterol: 2 g
Protein: 4 g
Fiber: 7 g
*I was sent some Heinz Seriously Good Mayonnaise to review, however all views and opinions are my own

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Syn Free Sweet Potato Fries


  • Eb Gargano

    17/06/2016 at 9:37 am

    Thank you so much, Cliona, for mentioning me in your post :-) So pleased they turned out well for you. Loving the combination of spices you've got going on there - sounds delicious! Eb x
    1. Cliona

      17/06/2016 at 9:38 am

      Thanks for the advice Eb! It made all the difference :) x
  • Martin @ The Why Chef

    17/06/2016 at 12:52 pm

    Oooh mayo and spring onion sounds like a good dip, and I always have these in the fridge, and never know what to have with sweet potato fries! I'm giving this extra long cooking time a go tonight - mine are usually a pathetic limp flop that embarrasses both me and the sweet potato!
    1. Cliona

      17/06/2016 at 12:54 pm

      The Heinz Mayo is delicious and works really well with the spring onions because it's quite smooth and mild! My other half had previously banned me from making sweet potato chips because they were so limp and sad, now he loved these so I must be doing something right! It just meant pushing past my comfortable cooking time! Thanks for commenting ?

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