Preheat the oven to 250° (480°F).
Slice kumara into 1cm rounds, then slice each round into fries 1cm wide. Place fries in an oven tray, pour over melted coconut oil and shake the tray until the fries are all covered.
Combine flour, cumin, sesame seeds and salt in a bowl and sprinkle over the fries, shaking again until the fries are covered on all sides with seasoning. Ensure fries are arranged in a single layer not touching each other, to ensure a nice, crisp bake (important!).
Fan bake for 20 minutes on one side, then flip and grill for 10 minutes. Watch closely to ensure fries don't burn, but instead become golden brown and crispy.
Remove from the oven and leave to sit in the try for a few minutes before serving, to allow the fries to crisp up.
To make the cashew aioli, blend all ingredients in a high speed blender or food processor until smooth, scraping down the edges as needed to ensure a silky smooth blend. You can keep any leftover aioli in the fridge for up to 4 days (it will in fact thicken on chilling, so if you want a thicker aioli you can make the day before).