Crispy Sweet Potato Fries with Chilli Mayo


This year I have bought some purple sweet potatoes to grow in the allotment.  I will probably grow them in the poly tunnel as they need a slightly better climate than the UK can offer, originally coming from central/South America. The purple sweet potato is one of the staples of the Okinawan diet in Japan, an area which is credited with very long life.  In this case the purple sweet potato is very high in the anthrocynins which are also found in blueberries, Blackberrys and red cabbage. The humble orange sweet potato doesn’t have these but they are still very high in vitamin A, B6, fibre, potassium and magnesium.

The one downside of sweet potatoes is that they have quite a high moisture content so are difficult to crisp without a deep fat frier. This recipe gives them a helping hand with the addition of cornstarch and a drying period in the oven.

If you want to serve these as canape why not serve them in little chip cones. You can use newspaper but make sure there is an inner cone of non printed paper so you do not get die transfer, plus in the UK you are no longer allowed to sell fish and chips in newspapers, which was a traditional way of using up left over newspapers, due to EU legislation. Now all newspaper inks are non toxic which they weren’t at the time but you are still not allowed to package anything in something where the packaging may transfer on to the food!

Serves: 4 as a side, 12 as a canape

5 a day: 1 per quarter of the recipe

Time: 45 minutes plus soaking time



  • 450g sweet potato
  • 2 tbsp salt 
  • 1 tbsp bicarbonate of soda
  • 100g cornflour
  • 1 tbsp smoked paprika
  • 1 tsp chilli powder
  • 1/4 tsp ground pepper
  • 100g polenta/cornflour
  • 2 tbs rape seed oil


  • 2 tbs mayonaise/vegan mayo
  • 1/2 garlic clove crushed
  • 2 tsp sriracha
  • 1/4 tsp paprika



Peel and cut the sweet potatoes in to fries. Soak in cold water for an hour then drain.

Bring a pan of water to the boil. Add the bicarb and then the fries. Boil for 3 minutes and then drain.

Preheat an oven to 200C

In a separate bowl add the paprika, chilli, pepper and cornflour to a bowl.

Add the sweet potatoes and combine until well coated.

Add 1 tbs of oil each to two non stick baking pans and smooth around the pan. If you do not have non stick pans then you might want to line normal pans with non stick parchment paper.

Add the fries making sure to spread them out well.

Bake in the oven for  10 minutes. Flip and then bake again for another 10 minutes

Meanwhile make the mayo by combining all of the ingredients.

Prop the oven door open, turn the oven down to 100C and allow to bake for another 10 minutes.

Serve immediately with the mayo.



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