Preheat the oven on 220c/gas mark 7/425f.
Peel the potatoes and cut the potatoes into thick rectangular strips trimming off any rounded edges.
Drop the chips into a pan of salted water with vinegar and bring to the boil.
Simmer for 6-8 minutes until the potatoes are partly cooked and tender (prick them with a fork.
Use a colander to carefully drain off the water, then rinse the chips to stop them cooking any further.
Leave until completely cool and use kitchen towel to blot them dry.
Meanwhile, pour the 80ml of coconut oil onto the roasting tray (you may need two trays) and heat up by placing the chip pan in the oven until it starts to bubble.
Place the chips in a large zip lock/re-sealable bag (you may need to divide the chips and the flour) and pour the 3 tsp of gluten free flour, starch and baking powder in the bag, seal and shake to evenly coat the chips in the flour.
Carefully remove the pan from the oven then lay the chips out on a baking tray and turning them so they are saturated evenly with oil.
Bake the chip for 25-30 minutes (turning them a few times during the baking process).